First, you will need :
1. .gif image (You can find it at google or you can make it by yourselft using any gif maker program)
2. spraygen (Find it here spraygen )
3. VtfEdit ( Find it here VTFEdit )
Now, lets make the the .vtf spray
1. Open up spraygen, Select Import > (Your .gif image)
2. Make sure the width, height, tick the "Animated" radio button
3. Select Convert to VTF
4. Name it spray.vtf , Then Close the
3. Select Convert to VTF
4. Name it spray.vtf , Then Close the
5. Open the spray.vtf using VtfEdit, make sure it works and the file size <500 kb="" span="">500>
6. Move your spray.vtf to Gmod spray folder on SteamApps\common\GarrysMod\garrysmod\materials\vgui\logos
7. Replace the old spray.vtf with your spray.vtf
8. Open Gmod, > Options> Multiplayer > Select Import Spray > Choose your spray.vtf on the SteamApps\common\GarrysMod\garrysmod\materials\vgui\logos
9. Done