Welcome! I agree that we need to know more about your needs and wants, where and when you'll be backpacking and expected low temperatures before we can recommend anything!
As a general rule, what most people want out of a sleeping bag is warm, cheap, light. Unfortunately, there's no way you can have all three at once.
If you haven't already found them, there are lots of excellent articles for beginners and on gear selection listed in the left-hand column of
http://www.backpacking.net/, the home page of this site.
Another good site for gear selection is
Mark Verber's website. Lots of ideas for gear, including low-budget alternatives.