How can I add a link in the forum summary page, next to the FAQ,Search,my profile,...links.
I want to link to a other page on my website (so a page that has nothing in relation to the ubb).

I guess it has something to with the public_common.pl page, but I can't figure out what to change.

in public_common.pl, search for sub MainButtonOptions

Inside there, you will find instructions on how to add additional items to that section.