The other reply was correct. Transferring a star is simple. I wanted to figure out how to sell it. I suppose that is also my fault of not understanding ethereum/nft terminology, not just Urbit.
The sales process consists of you transferring ownership to an address the buyer provides you after they pay you; it's not programmatic. The fastest/simplest way to sell is probably to list your star on opensea.io, though there's also a marketplace group on urbit.