starting problems

I have a 92 ford ranger. I engine won't turn over. The lights are very dim, which leads me to believe the battery is dead. But it won't boost, could there be something else wrong?

the batery may be too old to hold a charge. a multimeter will help check voltage. should be at least 12while not running and 14.5v while running.usually when a battery or an alternator goes bad it ruins the other so it is advisable to replace both.it could also be the starter if you can get the battery to a full charge of 12v and it still won't crank.