my friend who is catholic married a catholic in the church. They divorce. She remarried outside the church in a nonchurch noncatholic setting (wedding chapel in Vegas) to an unbaptised nonchristian. Her marriage to the first man has just been annulled because he wants to marry in the church. What does she have to do now to get married in the church.
She should talk to her priest about convalidation.
the story is confusing, but if I am reading you right that the first marriage was declared null, both parties are now free to marry. If either has since contracted a civil marriage they must make arrangments to have it convalidated, that is, witnessed by a priest or deacon. Depending on the grounds for the annulment, if there is a situation that must be resolved first, they may have to wait. For instance, if the grounds included some instability on the part of one spouse, before they could marry again they would have to prove that this has been remedied.
In your post, you do not mention if the man from the Las Vegas wedding was married previously. If he was, and the spouse was alive, she might have to initiate annulment proceedings for this marriage.
I do not know whether the fact that he was unbaptized makes a difference. The church attitude seems to consider secular marriages valid unless proven otherwise.