How do I overwinter ferns?

If they have fronds that die off over winter you can trim these off and store the pot somewhere with little light. If they are evergreen you will need to store them somewhere light. You don't say which part of USA you are in (add this to your profile as it helps with answering q's.) but I'll assume it is somewhere that has cold winters. Do you have a covered porch or windowsills where you could put them over winter? Does the garage have a window?

I live in North Alabama. So I can put them in my garage (it has some light). How often do I water? When spring rolls around do I cut it back drastically? Thanks so much