If you want to have a spray like the cool kids,
you can follow these directions:

1st ----- Find or create an image you want to use.
2nd ----- Download and install Half-Life Logo Creator
3rd ----- Launch HLLC. Click 'open' and find your image file.
4th ----- Adjust the size to your tastes or click 'autosize.' (NOTE: There is a limit to how long and wide your file can be. Autosize is recommended.)
5th ----- Check 'save it to' in the bottom left corner and specify a location where the file will be saved. (Remember this location.)
6th ----- Now, hit 'Make WAD' in the upper bar. Click it once more. It's retarded and sometimes doesn't work the first time.
7th ----- Exit HLLC. Find the wad file that HLLC made (hopefully you remember where you told it to save to) and rename it 'pdecal.wad.'
8th ----- Make a copy of 'pdecal.wad' and name it 'tempdecal.wad.'
9th ----- Copy these files to your cstrike directory (valve/cstrike for cracked version.). Overwrite any files if prompted.
10th ----- Make 'pedcal.wad' and 'tempdecal.wad' read-only (right click them and check the box that comes up).
11th ----- Delete 'custom.hpk' if it's in your cstrike directory (this includes 'custom1.hpk' 'custom2.hpk' etc.)

Your spray should show up in the game when you press 'T.'