Here's what you should do.

Go buy a multimeter from a store of your choice, don't buy a super expensive unit.. just one that can read voltage and current.

First, start and let your car idle. Put the leads on their respective polarities on the battery (Black should be in COM port & Red should be in VΩ set to DC V.. some read differently).

Whats the voltage of the reading? It should be north of 12 volts. If not, go rev the engine and see if you notice any change. If at no point you see +12 volts you got a problem with the alternator.

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Now turn the car off, take the negative cable off the battery and open that fusebox. (Remember to move your red connection on the meter from VΩ to 20A as well as move the dial to 20A). Put the leads to both the cable and the battery and see your reading. This should be a small number.. never higher than 50ma (0.05 on the meter). If this number is high.. then start pulling fuses.. whenever that number drops like a rock.. you got your electrical problem. Be careful that your not pulling so much current that the wires of the multimeter don't get hot and melt.

Hope this helps out!