Hi Becky, welcome aboard.
Ok, the first thing you need to think about is budget. Since you're new to the hobby, I wouldn't make a huge investment yet because you need to make sure you like it. Besides, even if you get a starter detector, it will make for a great backup machine when you move up.
The second thing you need to think about is where you plan to detect. There are two basic places: dry land and dry sand at the beach, and then there is the wet sand/surf or even underwater.
To start, you will probably want to focus on dry land and dry sand at the beach. Wet sand at beaches up to surf line, in my experience, don't produce many hits at all (its just the place people cross to get from their beach towels on the dry sand to the water). There are some great finds in the surf, but when you start talking about searching in the water, the cost of your machine will probably start at $700 and go up from there (be very suspicious of any "water machine" that retails new for less than that). You can start with a good dry land/dry sand detector for about $230 or less.
The two I would recommend would be the Garrett Ace 250 ($212) or the Tesoro Silver uMax ($230). I prefer the uMax, but that should mean nothing to you. It is about what you like. Check out both machines thoroughly and type in each machine in the "Search" box to see all the discussions about them. You will probably find every single question you can imagine already covered.
After that the only thing you'll want to get is a pouch for your finds, a digger, and if you plan to hit the beach frequently, a sturdy long handled sand scoop. That'll be plenty to get you started. Most of us end up getting all kinds of gear, whether we need it or not.
Again, welcome and good luck. You may not get rich, but you'll still have a lot of fun.
