Thanks a lot for your valuable advice!
In this case I had no issues in actually finding the right way, I was just stuck down due to the harness being hooked to the boom. The true problem was that I wasn't expecting this to happen since I had never been using the harness before and couldn't even imagine what might happen when falling backwards being hooked to the sail. Now I understand the mechanics much better and can imagine/predict such situations to happen. Hence, the next time I'll be very well prepared - both physically and mentally :-)

PS: I'd never ever stop surfing in my life even if it was supposed to be the last thing to do...:-)

Hang loose, oh yeah! Haha