check fuses first.. then buy yourself a digital multimeter that measure VDC (direct current voltage just in case you didn't know ).

with the car off you should measure about 12 V+

with the car started and the alternator working correctly, you should measure from 13V+ to 14.5V+

if you measure this voltage, then your battery may not be holding charge.

if you don't measure this voltage, check the ground strap and grounding points on your engine and your battery. if that still doesn't do it, you'll have to take your alternator off and test it.. good luck :thumbup: