You can pay it online at www.payncticket.org. The ticket should also have instructions on how to mail it in. Clerks of court do not accept personal checks. If you have lost the ticket, go to the clerk of court in the county where the ticket was issued and they can take your payment.
This is one of the few charges where just paying it does not have a lot of extra consequences. For example, if you just pay a speeding ticket, it can cause your insurance to increase for three years and in some cases, depending on your record, even lead to a suspension of your drivers license. It is always best to consult with an attorney who handles traffic matters before paying a ticket. In the case of a seat belt violation, however, there are no insurance or license point consequences.