MyBB Community Forums

if mybb is a forum how to turn it to a support site just like google support or mozilla support
how to?

A support or ticket system is not a MyBB core function.  There was a plugin to provide this functionality, but not updated since 2015.  Which is problematic given the changes to the MyBB core since then.  And wouldn't be "just like" anything else regardless.

Hesk is a free support site, if that's what you want. If you already have a mybb forum and you want to add support, the best way to do it is to create a subforum where anyone who posts can only see their own threads, but admin/moderators can see them all.

This community uses the MySupport plugin mentioned early.