This might be a stupid question, but can anyone explain to me how to create custom decals? Also, once they have been created and added to the workshop can other players see and use them in game?

If anyone would kindly consider making me a decal, based on this, I'd be very grateful:

http://cdn.akamai.steamstatic.com/steamcommunity/public/images/avatars/7d/7de7ff32ba7877f50f79ced919d8b9d9f9b1a47b_full.jpg