If they're flickering, you could have a bad connection somewhere. I would take the car to an Advanced Auto or other parts store and have them test the charging system to see if it is putting out the proper voltage. If you have a DVOM, you can do it yourself. You should see 12-12.6v with the engine off and 13-14.5 with the engine running. If you've got less than 13v with the engine running, your alternator is not charging.
If you find out that your alternator has failed, try to find a good used one to purchase. The alternators that parts stores sell are complete junk and rarely last more than a year.