My b2evolution Version: Not Entered

I have a bilingual blog, that is my posts are displayed in german as well as in english (see http://forums.b2evolution.net/viewtopic.php?t=7865&postdays=0&postorder=asc&highlight=bilingual&&start=0). I would like to change to V2.x but I am a bit lost how to do it. Can someone help me?

Thanks!
Anne