How can I register my horse?

So I bought my horse as a rescue when she was about 1 and a half, the guy I bought her off of told me that she was a Quarter Horse and that was it. He didn't give me a registered name, or name's of her dam and sire. And now she's almost three and me and her are starting into getting into showmanship and at most shows I would like to take her too, papers are required that and it would just be a good thing to have. Could I send in a blood sample or something? Cause I'm really stuck here, haha. Thanks for all your help!(: