Hi Lisa!
Great question. Since you're bike wasn't used much last year, I'd recommend bringing it in to a bike shop for a basic tuneup. This would run anywhere up to $40 depending on the shop, and they will perform basic maintenance on your bike to ensure that it is in proper working order. A tuneup should include adjustments to your brake bads, brake and shifting cables, tires, and attention to general bike health.
If you prefer to take care of your bike yourself, Bicycling.com has an excellent
Bike Care Calendar that tells you what you should be doing each month of the cycling year.
Happy Riding!