you've got an electric motor on it?
I've got an 87 235ic E30, which I guess could be really different from yours, but it's easy to put my top down once you get the gist of it:
1. unclamp from windshield, push front piece up just a little bit
2. once front piece is bent up, pull rear window piece up -- this should cause front piece to bend up more. pull rear piece up until there is enough room to lift the plastic cover (after pulling the cover release latch and then sliding your finger into the drivers side under the latch and pushing another release)
3. push the rear piece into the compartment which should cause the entire top to slide into the compartment. BUT - if while pushing the rear piece into the compartment, you see the top piece flatten out (like it is when closed), you must bend the front piece up again.
hope that helps, but it sounds like maybe it won't