OK, I see it now.
When I install jbpm Designer version 3.0.8 then there is the context menu entry "Deploy Process Archive" in the eclipse package explorer.
When I install jbpm Designer version 3.0.9 then the context menu disappears but instead I get a new tab "Deployment" in the Process editor and I can deploy through this (even more comfortable) mask.
Actually I remember now that in the starters kit user guide that deployment mask was viewable in screenshots. But as starters kit is bundled with version 3.0.8 of the designer, it did not show up.
So, forget about this posting... ;-)