Useful tutorial:
How to create and put your own spray!
First STEP:
1) You must download "HL TAG CONVERTOR", which is found--->
here.
Second step:
2) Open HLTagConvertor.exe Then this will show up:

Third step:
3) Click on "Open Image", then get your own photo..

4'th step:
4) Once you get your own photo, you should make it transparent view, so it could be like this:

Transparent view's benefit: It remove whole the background.
So, if it's without transparent view, it will be like this:

5'th step:
5) Click on "Adjust image" then "Apply changes and convert colors to 256".
6'th and the last step:
6) Click on "Save tag" then "Export to WAD"
Save the file as this name "tempdecal" in any file.
Once you save the file's name like this , take the "tempdecal" file, and replace it with the current tempdecal in cstrike.
*WARNING*: If you changed the spray, which I mean.. from chicken to skull spray, for example.. your own spray will be deleted.
And now, you have your own spray!
Have fun,
Yours,
h1x.