Diggles: don't be embarrassed, if you can't ask it here where Can you ask it!
For the price range you're thinking about, you can get a hybrid bike. It's not a road bike Or a MTB, it's more like a commuter/comfort bike. You can get one for under $500 and see if you like riding and/or how much you'll ride it. The hybrid bikes tend to have straight across handlebars so you're going to sit up, the tires are thicker than skinny road tires and they are built for comfort. It's a good place to start tho to see if this is what you want to do.
I'm not very familiar with some of the other brands - the other ladies are tho and can offer suggestions but I'm thinking along the lines of the:
Trek Navigator 200 or 300. We've got a lady here on the board that just did her first century on the Navigator 300 so don't poo-poo the hybrid-ness of it!
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"