Need help with Login for my site. Need help asap!

so basicallyi want a login page that when you log in, you see content thats meant for you, you can't talk to other people or anything, just site admin.


For context , i am going to have a video editing business, and i want them to log in then be able to upload video clips that i can download then after done editing i re upload the result to there CP, i drew a very epic 10/10 visualization of it.



My question is how do i do this? You don't need to explain word for word in comments link me a resource if you have one ETC! Thanks! :D