Got it. I had my Soldat path changed. Niko -
1) make sure you have WinRar 3.0 or higher
2) in Settings tab, set the correct paths for Soldat and WinRar
3) back to the Main tab, you should see all your maps in the left window. If you don't, something else is wrong and come back here.
4)Pretty self-explanatory from here. At the bottom, put a path for the (new) archive you want to create. Drag some maps into the right window and create.