What do i do to sell php scripts? Do i need to register script mark before starting to sell it? Do I need a special license to sell online? Im pretty confused :\

It depend of the script.
If you wrote it yourself, then you just need to find peoples interested in you scripts.

If you did not wrote them yourself, you need to check on the licensing terms to know if you are entitled to either pass your license to someone else, or to gain money by distributing it.
Some scripts don't want anyone to distribute their work for money.

If you are all clear, then as if you wrote the script yourself, you just need to find customers.

Yeah i wrote it myself. But before i start to look for customers i need to set up a license for commercial purposes, do you know any guides that could help on that task?