After creating your own GMod spray, you will be able to place a picture on the walls of the Garry's Mod, or GMod, map you are currently playing on. Every game that uses the Source engine from Valve Corporation, such as Half-Life, Team Fortress 2 or GMod, allows players to import custom spray pictures. Players can then spray those pictures while in-game to, for example, share a funny picture with their friends. You can create your own GMod spray by using Paint, a graphics editor you can find in your Windows installation.
Open the Windows Start menu. Type "Paint" in the search field. Then press "Enter" to launch the program. When launching, Paint will automatically create a blank picture that you can then edit to create your spray.
Click on the "Home" tab and select "Resize." Then click on "Pixels" and deselect "Maintain aspect ratio." Finally, type "128" in both the "Height" and "Width" fields and click on "OK" to resize your spray image to the appropriate size, 128-by-128 pixels.
Customise your spray by using Paint's editing tools. In the "Home" tab, you can find many tools that allow you to personalise your picture. You can use the "Text" tool to insert text into the image, the "Shapes" tool to create various shapes and the "Paint Bucket" tool to fill those shapes with colour.
Save your spray by pressing the "Ctrl" and "S" keys simultaneously on your keyboard. Give a name to your spray and select ".bmp" in the file format drop-down menu. Finally, click on "Save" to save the spray on your hard drive.
Click on your Windows Start button. Then select the "Steam" shortcut in the "Steam" folder. Log in to the program if needed. Steam is the program that allows you to launch GMod.
Click on the "Library" button and select "Garry's Mod" in the left-hand pane. Click on the "Play" button to launch the game.
Click on "Options" in the main menu and then select the "Multiplayer" tab.
Click on the "Import Spray" button. Then use the file browser to locate the file you created earlier with Paint. Click on "OK" to finish importing your spray into GMod. You can now use that spray in all multiplayer GMod games by pressing the "T" key on your keyboard.