Horticulturally Challenged

I admit I am truly horticulturally challenged. Yes, I had to go look up how spell that word (:

Anyhoo, I was at a antique flea market last weekend and brought home two large tomato plants. My husband saw them and said "Who buys tomato plants at a antique flea market?"...Men.

At least I think they are tomato plants. Wouldn't that be too funny (NOT) if I bought a couple potted weeds....or maybe Cannabis plants (Did I say that outloud?). No, they aren't that...not that I've ever seen any. OK, so I have but it was ages ago when I lived in Hawaii. The stuff grows wild there I swear. Well, the guy that sold these to me just better hope they start popping out tomatos or I'll have a dissapointed, crying 7 year old and then you know I'll just have to hunt him down. *grin*

Apparently they yield medium to large tomatos. So now that I have them what do I do with them? Do I leave them in the pot or do I need to transplant them? How often do you water them? The guy that sold them to me did say that the soil already has fertilizer mixed in. So that sounds like a good thing.

I've never had a knack for growing things. Even managed to kill a couple cactus in my day. So I could use some advice. My 7 year old is excited to see how many tomatos we'll get. So I REALLY don't want to end up killing these, so any advice is appreciated (: