you wont need to dry them but make sure the tomato is ripe before you grow them. Also they may not come true to the tomato you got them from, but they will still taste ok.
I've also done that with sweet peppers.

Great, thanks Seaburn I'll give it a go.

If I had a nickel for every tomato plant growing in my compost pile, I'd be a wealthy man!

If the variety is one of the so called heirloom types and not a hybrid it should come true from seed

I save & grow my own "yellow balcony" seeds without any trouble

I save my seeds each year from tomatoes bought from the supermarket. This year I've got large beef toms and various small cherry and vine growing plus a few different chillis. You don't have to dry them but when I do dry at the end of the year for storing, I put them on kitchen roll on a radiator. Usually dry and ready to store within an hour.