How create Tabbed Menu ?

Sorry but i don't understand your reply :(
No template to modify ?

I dont get it can you explain it more so I can answer you?

you need to install mytabs plugin, have all what you need

You can install the plugin the handle the tab portion of the site and then manually code everything else outside of the plugin. for example, you can use the plugin to name your tabs, set which forums show up on each tab, then delete all css associated with the plugin and then manually add your tabs to the index template.