Which version you on about? Source or 1.6? Source you need to make a jpeg or Gif either 128 by 128 or 256 by 256, then in options in game you import a spray to where you saved it. For 1.6 you need to download Wally so you can make your image into a .wad then you rename the file pldecal (or something) and put in you cstrike folder.