buy yourself a digital voltmeter.
check your battery voltage after parking overnight. First switch on the headlamps for 5 or 10 seconds, and wait for about a minute then check your battery voltage.
if its 12.6 or 12.7 (battery is 100% charged)
if its about 11.9 or lower - your battery is completely dead.
second, if the above tests pass - start the engine and wait for the fast idle to disengage. - on a fully warm and operative engine, with no cooling fan or anything running - check battery voltage - it should be about 14.00 to 14.40 volts.. when the cooling fan kicks on the voltage should drop but pick up again to about 13.9 or 14.0 with the fan still running. This behaviour should also be seen with the headlamps activity.
If not - then check for voltage at the alternator output terminal - of different - the main wire is damaged or corroded. - if same - proceed to full field the regulator - theres a little hole on the alternator back plate that should point to the carbon brush holder screw, take a little screw driver and touch the screw and the case, the voltage should rise to about 15 or more - (your alternator is OK)
Connect a jumper cable to the negative of your battery and then to the engine lifting hook - if you see a voltage increase, your ground connections are bad. Redo the ground and your problems will be solved.