If you want your AC to work tho all you have to do is follow it to where ever it is leaking from the A/C system. Since you can see it that typically means their is a large like like a seal blew out or a hose has a hole in it. Find the leak and fix it you could probably get it working again
Definitely what you're looking at is A/C refrigerant leak dye....however I'll bet your compressor shaft seal is blown. Mine had the same problem whenever I would turn on the a/c. A new compressor was/is the fix.