I haven't opened one, but if you want a franchise it seems to be about $400,000 to $1000000 in cash/assets etc that you need.
Most places have information on starting franchises on their websites. For example the following companies have info about starting and opening a restaurant in their chain. If you want to do a franchise from some place look at their website and contact them if you have more specific questions. If you want to open your own unique place then I don't have much advice.