To sign up for Discover Scorecard, click below. Let's you get a free FICO score from Experian, and check it every 30 days. FICO is the scoring model most lenders use, so going to be more accurate for you than the free services online using Vantage model.
IF I sent you here directly it's because you need to build your credit history with new information, while we are working on trying to correct the erroneous information. Now I typically recommend the Discover Secured card, but have been getting feedback of some people being turned down. IF this is the case for you, the link below will send you to some other cards that can help you establish credit.
Once we have your score high enough, and IF you need to establish an additional credit line, I highly recommend the Discover Card. They have no annual fee, offer 12 months no interest balance transfers and you can get your Transunion FICO score included. They have 1-5% cash back depending on what you purchased and a cashback bonus match for the first year. Just a great all round first primary credit card to have.