just forge ahead. If you've made other breads, you can make sourdough. This recipe fives a lot of detail.
I find sourdough takes a longer time to rise no matter what the directions say, but it's worth the wait.
The percent hydration is lost on me. It has to do with how wet the starter is. It can be just moist, like a soft dough, or very wet, like a batter. One is supposedly more sour than the other. (don't ask me which).
Once you have a feel for how moist the finished dough should be you'll have no problems.
Link:
http://www.finerkitchens.com/swap/forum/index.php?action=display&forumid=1&msgid=83455
Do we find happiness so often that we should turn it off the box when it happens to sit there? emf