You need to register your UA marriage in Thailand. This is a bit more involved then just saying your married ad producing a valid marriage certificate, it is a long cunersome process unto itself..
Is you marriage recognised by the Thai Authorities? What is your country of passport? Where were you married? Any children? What region in Thailand do you plan to live?
It i painful when required as the person who owns the place you are staying at has to be registered. you can book into a hotel for the night and they will register you,