Before doing anything, ask yourself if you can settle the dispute. The other person or company may be amenable to negotiation. That way you avoid court courts and legal fees.
If you can't work it out, then you might decide to hire a lawyer and go to court. If the dispute is for a small amount of money, it might be better to represent yourself. Each state has the equivalent of city court, small claims, minor disputes and major ones. You need to know what the dollar sum is before you select a court.
The larger the dispute or the more complicated it is, and the more sense it makes to hire a lawyer. Remember hiring a lawyer means you pay the legal fees and costs of experts. The other side is rarely ordered to pay your expenses in litigation.