If you committed to providing coillateral for the bail, then you're committed. If you didn't, then you're not. If you need specific documents that you've signed reviewed, you're going to have to get your own lawyer.
I'm only licensed in CA. Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
If you haven't signed anything (or strongly implied that you would) you are not liable.
If you do sign, are you guaranteeing that the bail bondsman's fee will be paid (then you are permanently bound as soon as you sign) or that you will pay the bail if the friend fails to appear (then why do you need a bail bondsman)?