Bob's advice is actually good for a good bit of back ache. Rolling back and forth will loosen the erector muscles and help to push vertebra all in the same direction towards alignment.
It's not that good for lateral misalignment, but it could help with frontal / dorsal misalignment.
But Mikey, I'm guessin' that your back is tight (if it's the lower, from about the kidneys down) due to tight psoas muscles. They originate from the mid lumbar (L3,4 and 5, if memory serves), and connect to the inner groin area on each side.
What happens when they're tight is that they pull your hips "up" so that you don't stand erect naturally. As a result, so that you can stand up, your lower back becomes more arched, which causes muscles to be tense and eventually causes them to spasm.
(It's a common condition and aggravated by any "spare weight" you might be carrying around your waist, which pulls your hips further forward.)
Does your back get "achy" when you lay flat on the floor? And does it help relieve it if you bring your knees upward and put your feet flat on the floor? If so, it's definitely an issue that includes the Psoas being too tight.
There are various deep tissue releases that someone trained in Neuro Muscular Therapy is familiar with. And there are techniques taught in good Sports Massage programs as well that address the condition.
One of the best things that you can do for it personally is like an, "American Splits", in which you do an exaggerated lunge motion slowly. You'll have one leg in front and one behind you. You want the one behind to be far behind, as in a front to back split.
The focus is to stretch the back leg, with an emphasis on the front pelvis. Go to as low a position as you can and when you get there, shift your weight forward slightly. You'll feel the pull in the area I described when you're doing it correctly.
Massage doesn't have to hurt, BTW... And massage by someone who's qualified will help. But still, seeing a chiropractor would be a good idea... or better yet, an Osteopath.
