What settings should I put to .htaccess
There are no required .htaccess values for running Gibbon. Gibbon does come with a few rules, but these are not vital, they just make it a little harder to check out the database structure (although as an open source system, this is all available to anyone anyway).
You could use .htaccess to set some of the Post Install & Server Config values show here:
Although, that is really only needed on a shared server. If you have control of your server, these are better set in php.ini.