First, you can check if there is a credit report in your name with any of the major credit bureaus – TransUnion, Equifax, and Experian. If you receive reports, read them to make sure all information (especially your personal information) is correct. Any error can be disputed with credit bureaus directly.
After that you can apply for a credit card to start building your credit. We would recommend getting a secured credit card as they are designed for those who want to establish their credit. For example, you may like the Discover it® Secured card based on your expenses. This card will allow you to earn up to 2% cash back at gas stations and restaurants and 1% cash back on all other purchases. Please note that this card requires a security deposit which should be paid when you are approved for the card. The minimum security deposit is usually around $200 and it will get you an equal line of credit.
Since you are starting your credit, make sure you are always on-time with all credit card monthly payments. Try to never miss or be late with a single payment, it will help you to build good credit record. Also, try not to use more than 30% of available credit. Ideally, you would want your card balance to be below 10% of available credit or paid off each month. This will allow you to build good credit history from the start.