that for example if im selling something, and i create a list...after some minutes i can't edit the post right?
so if i want to update my list have i to do a new post every time? so is difficult for who reads to know what post is update and what isn't...how to resolve this problem? or maybe is there a resolution that i can't find? xD

Yeah you can't edit your posts after 30 minutes.

You can update your thread after the appropriate 4 hour periods or you can follow this guide that teaches you how to update your first post without editing.

http://forums.d2jsp.org/topic.php?t=26027073&f=34

ye but if my list is really big, i can't make a screen each time don't u think?

Well that is the only solution, or you could just say "this item has been sold"

it's not easy but if is the only solution i'll do so...