Offering a contract if it's with a realtor?

[Alfred Green]

I've got friends trying to sell homes while they're upside down in their financing. My question is basic to most real estate, but I don't know the answer.

If they've got it listed with a realtor, can I walk in my friends' house, present my offer, produce a contract, and be legal in it? I don't know if there are any legal boundaries I need to be aware of.

I'm glad I can ask here.

Alfred Green