You should talk to your teacher, don't say "Omg I think u are crap..." but calmly explain that you are having difficulties and that you don't know what she is talking about, she probably assumes you know it all because no one speaks up (I've seen this happen in my uni classes often).
Don't panic, get the book out, slowly read over things and make notes as you read them, if there is something you don't understand look it up in another book, ask your teacher or ask here. You probably know more than you think, especially if you are writting it in your own words, we used to copy it out (which I can tell you isnt that effective).
Its not such a bad thing that she doesn't explain too much, since in uni they rarely explain anything
Find your study method and stick to it, it is possible to do fine on your own or meet up with friends to study
You are just panicing, only now do I see how stressed I was for no reason. It will work out, just take charge and do somethign about it
If you need anything, i'll do my best to help - Mel