This tutorial will show you how to make a custom spray logo from scratch in Photoshop.

If the logo you want to make needs transparency (meaning it won't be a 256x256 square spray with a background), then check out the spray transparency tutorial.

Create a new 256x256 image in Photoshop.

Now you need to paste in the image you want, or create something from scratch.

Once you're done, you need to save it as a TGA:

File > Save As...

This was an extremely easy tutorial. All you need to do now is open the game the spray is for, then use the options menu to import the spray.