BG nailed it...you dont need to know much of ANYTHING...that comes in due time...the more you get into it, the more you will accidently learn...and then you will find yourself trying to learn more and more...

my suggestion, set a price range for a completed bow and arrows. head to the bowshop. tell them you are looking into getting into archery and am looking to buy your first bow. tell them you have XXX$ to spend on a completed bow..any good bowshop will take care of you..

and no, it doesnt need to be costly. you can find used bows fairly cheap...i had my buddy flinging arrows with 130$ spent total and his setup wasnt half bad for a first...

also, dont be afraid to post questions...lots of good, knowledgeable guys here willing to help...

good luck