Poblems with electrical?

We recently bought a 99 alero and were driving it for a while, then all the lights came on and the gauges wernt working, bought a new battery and it did the same thing, it was the alternator not working so the care was running just off battery and it cant run very long befory the battery dies. Here we have an advance auto and they will do a free bat and alternator test, maybe try that again. GL