Provisional patents are essentially place holders for your idea. You file one and its "saves the date" of when you had the idea!
You can do this online at the USPTO website, or hire a lawyer!
You don't need many details. Just jot down what the idea is and how it work. You want a higher level description. Be sure to emphasize the part that you really want to protect!
Just for a year! In that year, you have to work your idea, hammer out details & file a real patent. If you don't file anything within the year, the provisional goes away too.
If you do it on your own, a few hundred dollars. With a lawyer, you'll also pay legal fees.