1) Check your actual credit score at www.annualcreditreport.com. It’s free once a year for everybody
2) Start with Capital One Platinum card (no annual fee for 1 year and you will not need this card for another year).
Another option is Capital One QuicksilverOne Rewards card with $39 annual fee.
Your credit limit will probably be in $300 - $500 zone.
3) For more aggressive credit building you'll need an installment loan. Get one of the 12 months credit builder loans from a bank or credit union.
4) Use your card for 6 months.
5) After 6 month of Capital One card use, apply for a Discover IT card
Important: Never use more than 7-10% of your total credit limit inside the payment period and always pay off your balance in full several days before the deadline.