suggest can edit your post on main web

i suggest can edit what we post on main web
and there a log what we post before edit it
i hate to post down of my post if i forgot to add some sentence
it just like a spam if i do that

No, because then you can spam/changed your links.

ex. I'm you a regular user. I write "well thought out comments" that get approved by the mods. Then after some time has passed (ie more comments have been added to the site to hide my next move) I edit my comments to be some spammy stuff, or if I posted a patch link I can make it go to a virus now, or I could change a really cute picture into a grotesque one, etc.

As for the forums nobody really reads it so its okay to have the edit feature as there's such a small number of users to keep in check.