Angie, I know your post was about finding a good bike light but after looking at the photo of your bike I think it needs to be said that you really need to do something about the seat on your bike. With the nose of the seat ( or saddle if you may ) in the position that it is in...that can't be very comfortable. The nose of the saddle should almost always be parallel with the ground. If it's not you need to get the seat adjusted. Either that or in my opinion, buy a better seat. If it were me I'd recommend a better more comfortable seat. You might try something like these. These seats are usually for people who are "recreational riders" and are what you see a lot on the type of bike you have. Notice in the link that there are other similar seats and some with LED red lights built right into the saddle.

Anyway, if you buy a better seat you might want to take it to the nearest local bike shop ( LBS ) and have them help you set the seat up properly on your bike. More than likely they will do this for free.