ok so basically I made this guide back in 2014 and it's so ♥♥♥♥♥♥♥ awful so here's me fixing it

So there's a few things you should consider before making a background for Garry's Mod.

-All backgrounds were created with a resolution of 1280 x 720.
-Every screenshot in the background folder is jpg, if you really want you can also use PNG even though I've never tested it myself.
-If you can't think of something to make, you're probably not ready to make a background.
-It really doesn't matter what the background is. It doesn't even need to be from Garry's Mod. Hell, if you must, just make your background images of spaghetti.

That should be the basics, the next section goes over...well, find out yourself.

This is an optional step, you don't even need to do this unless you want to create something of your own.

You don't need to have a guide to explain how to make poses. This is a guide on how to make things backgrounds, not how to make things in general.

After you've finished making...whatever you want to make, whip out yer camera tool, get a good angle and smash your finger on the left mouse button. In the case your primary fire isn't bound to left click, leave this guide and re-evaluate your ♥♥♥♥♥♥♥ life decisions.

Alright, so you either...

*made a cool and good background
*stole someone else's work because you're either lazy or untalented
*got an image of spaghetti from the Internet (best idea)

Whatever the hell you did doesn't concern me at all. What you need to do next is find the location of that screenshot. If you already know where screenshots are, or you're using something that is not a screenshot of your own, go to the next step and follow the instructions there. If you don't fall in that category, stay here, I'll have to hold your hand and show you where it is myself. Goody goody.

Okay so, in normal circumstances, Steam saves every screenshot for every game in this directory:

However we're not heading to that because the way I go is much more simple.

Now here's where things can get...weird as ♥♥♥♥. You might notice some screenshots are saved in .tga format. .tga format can be opened in programs like Photoshop, GIMP, (don't quote me on that i'm not entirely sure) and paintDOTnet. From what I've seen, these screenshots are .tga because they're not taken using the camera tool, they're taken with Steam's built in screenshot button. Notice how I said that you should take screenshots using the camera tool, not the built in button. You should never use the F12 button unless you REALLLY need to. If you took your screenshot with the F12 button and not the camera tool, you're either going to have to retake the image or convert it to something convenient.

If the image you got is in JPEG format, you're on the right track. The next section tells you how to move it from the screenshots folder to the backgrounds folder.

Okay, let's recap. You got the image you want, you've found where it lives and now we want to put it in the background folder.
Okay so before you do anything, right click the image you want and copy it. Feel free to check its resolution. It doesn't really matter what the resolution is but from what I've seen the default backgrounds are 1920x1080 but I doubt it should make a difference if it's a different resolution.

What were we talking about again? Oh yeah, you copied your screenshot and now you're gonna shove it furiously in the background folder. By the way, that's located in .
If you're doing everything right the screenshot you wanted to put into backgrounds is...well...in the backgrounds folder. You don't have to rename it or anything, it should pop up randomly.

I guess you're done, there's a celebration planted into the next section.