last time i tried i totally screw up
does someone know how i move from /community/ to public/html ?

Go into your admincp and be sure to change the url to your forum, admin and mod cp's & style images. Then move the files.

If your planning on using a different index page than the forum index, theres an option in the admincp to use a file name other than index.php. Rename index.php to forum.php or whatever you want and make sure you link to that on your sites index.php page.

Don't forget to update your license details over at vBulletin.com to point to the right directory.