Bought a new bike!

I have been riding a Schwinn cruiser. I love the comfort but really feel beat up after riding 10 miles so made the trip to my town's bike store. I came out with a Fuji Crosstown and love it. After just putting a couple of miles on it I am enjoying the ride. The shifting is so much smoother. I am basically a stress reliever rider and stick to bike trails. I just need to figure out these speeds. I have never had a bike with shifters on both side of the handle bars. Any tips would be appreciated.