How to Apply for a Marriage License. Follow these step-by-step instructions to apply for a marriage license at one of our office locations.You can get married in any county in Florida, regardless of where you obtained your marriage license. How to order a Florida Marriage Certificate. Additional resources include a directory of local self-help centers. Step 1: Make sure you meet the eligibility criteria, such as age. Step 2: Fill out the pre-application in your county online. Have questions about how to get your FL marriage license in the mail? ULC ordination can be completed online, free of charge, and will provide you the power to perform legal wedding ceremonies! Couples wishing to become legally married in the state of Florida must apply for a marriage license in person and be of 18 years old and over.