How to make posters in Garry's mod?

Hello guys, recently I started to be interested in creating different art in Garry's mod and I had a question, where is the best place to make posters in Garry's mod? and is there a difference between the programs?

I hope this post and the answers under this post help beginners

camera angles. zooming in more would get rid of a lot of negative space and create more emphasis on your scenes. you could also play around with lighting (you might have to dig around the workshop for lighting specific addons, i can’t name any off the top of my head currently) and when you think you’re done with a poster, fool around with post professing effects, in gmod and out (photoshop, pixlr, gimp etc. even the photos app isn’t bad)