I bought a new battery for my 2004 honda civic and the battery light on the dash is still on. Does that light have to be reset? Or is it my alternator::confused:

Try to disconnect the battery for an hour or so. If that doesn't work... you may need to have the code reset by a mechanic. Usually, though if you disconnect the battery for a while, all the codes should reset. There is always the electrical tape option... just cut a piece of electrical tape and apply it to your gauge cover to block your menacing light from view.

Likely, it's the alternator. With the engine idling, check for 14 to 15 volts at the battery, using a multi-meter. Most auto parts stores will check alternators for free.