Beginner's Guide

You should now have a little walk around, and get acquainted with your surroundings.
When you are ready, hold down Q to open the Spawn Menu. To keep it open, you need to keep Q held down. Look at the lists of objects, then click on and object's icon to spawn it. You should be aiming/looking at the ground in front of you, because when you spawn something from the Spawn Menu, it spawns right in the direct center of your screen. This is shown by a few dots in the center. Releasing the Q key closes the spawn menu.

Now that you have spawned some objects, I bet you're asking yourself, "How do I move this stuff around?". Well, you should be holding a weird sort of gun in your hands, glowing blue by default. (It's shown in the image above) This is called the "Physgun", being short for "Physics Gun". It allows you to manipulate objects and other stuff in the game. If you are not holding it, the scroll wheel on your mouse allows you to select different weapons and tools. When you have highlighted the weapon/tool you want to select, just left click! If your mouse doesn't have a scroll wheel, the number keys (1 to 6) can be used to select weapons/tools instead. With the physgun equipped, aim at the object you spawned and left click on it. As long as you have the left mouse button held down, you will be "holding" it with the physgun. If you move the mouse around while holding the object with the physgun, (Keep left mouse button held down) it will move around with the camera. If you hold down E while holding an object with the physgun, you can rotate the object by moving the mouse around. Pressing the forward or backward movement keys (W and S) with E held down, you can move the object forward and backward! This can be useful for placing stuff in/onto places or other stuff with precision. If you right click while holding something with the physgun, it will freeze that object into place. Pressing the R key twice will un-freeze everything you have frozen. Please note that NPC's (Non-Player Characters) and vehicles cannot be frozen, even though vehicles will show the green flash effect that is given off when something has been frozen.

If you ever want or need to fly around the map to get to a particular spot, or to get up close to a usually inaccessible part of something you're making, you can use the "No-Clip" mode to fly around and go through stuff! It is, by default, toggled with the V key.

There are many, many things that can be done in Garry's Mod, like building rockets that people can ride, super cars that go as fast as lightning, catapults that shoot stuff over long distances, there is quite a damn lot of things you can do in this game, but it's even more fun when you can do all this with other players! See the next section on how to play online with other players!
3. Playing in Multiplayer
YOU MUST HAVE A WORKING INTERNET CONNECTION AND A CONNECTION TO STEAM FOR THE STUFF IN THIS SECTION!!!! I CANNOT BE HELD RESPONSIBLE FOR ANY CONNECTION CHARGES OR FEES FROM YOUR ISP INCURRED FROM THE ACTIONS PORTRAYED IN THIS SECTION OF THE GUIDE!!!!

In this section, we will play on a Garry's Mod multiplayer server with other players on the internet!

First, pause the game by pressing the Escape key (Esc). It will pause the game for you, and show you the menu, as seen below:
Click on "Find Multiplayer Game". This will show a list of gamemodes in use by all servers. For now, you should search for, and click on the one that says "Sandbox", with the icon being a wrench. I could not take any screenshots of the multiplayer server screen due to some limitations. I apologize for this. You should then search for a good server that has a low ping, (Higher ping = slower connection to server/high traffic on server) is in your country, is not empty or full, and the map it's on is either gm_construct or gm_flatgrass. If the server has custom content that you don't have, (E.g. Custom map, object, NPC, vehicle, Tool Gun tool, etc.) it will automatically download it for you while connecting to the server. When you have fully connected to the server, you will spawn in the map just like in singleplayer, except there will also be other players playing in it too. While you are there, there is a couple of other things you should know first: pressing the Y key lets you type in a message to send into the server's chat, letting you talk to other players. With some configuration through Steam and a little bit of settings tweaking, you can also use a microphone to chat to other players! Also, you can change the appearance of yourself in multiplayer by opening the Player Model menu by holding down the C key, then clicking Player Model. You can change the looks of your character, their color, and also the physgun's color, too! Changes to your player model take effect when you respawn, by dieing or disconnecting from the server, then reconnecting. Have fun playing with other players! Make sure you don't misbehave on it though. It could get you automatically disconnected from the server, (Known as being "Kicked") or even banned from it! See the next section on how to download addons from the Steam Workshop!
4. Addons and the Steam Workshop
WARNING: Some of the content on the Steam Workshop may be inappropriate for younger players. I recommend that younger players first get help from an adult before heading onto the Addons menu! After all, the majority of Steam's userbase are mostly older players...

In this section, we will look at the Steam Workshop, a service on Steam which allows users to create, download, rate and share addons for various games on Steam, including Garry's Mod.

An "addon" is a small modification for a video game, which could be a new car, gun, prop, map, etc..
My guide on how to create maps for Garry's Mod explains how to upload addons to the workshop via the game's creator's uploading tool, although every type of Garry's Mod addon (Except maps)
can be uploaded in-game.

First, we return to the main menu. There is a button that says "Addons". Click on it. Now, there should be a massive menu containing a bunch of stuff with lots of pictures and text. These are all addons made by other players! There are many types of addons available, but you should try looking for a good map. Click on "Maps", then click on "Top Rated", if it's not already selected. Search for a map, and if you think it looks good, hover over it, then click "Install". Garry's Mod will then start downloading the addon. Once it's finished, you will be able to try it. If you want to make your own addons, it is EXTREMELY complicated!! I have a tutorial on how to make a map for Garry's Mod here, however you will need another game that is built on the Source engine, and the Source SDK for it. See the next section for the conclusion to this guide!
5. Conclusion
In this guide, you have been taught how to:

1. Play the game, duh!

2. Connect to a multiplayer server

3. Download addons for the game

Now, the guide has come to it's conclusion. Most of the stuff you will learn about the game will be discovered by yourself. What you should do now is maybe go onto the forums and ask for some help with the game, jump onto a multiplayer game and ask some players how to do certain stuff, etc.