I've seen an uptick in the use of foam rollers among people of all activity levels. This is fantastic! Even if your activity consists of sitting at a desk most of the day, you're going to get knots and tightness that will eventually cause back and joint pain. Get a foam roller!
What I also often see are people just rolling up and down the roller. Kind of makes me think of how Egyptians used to move large bricks. This is a start, but won't give you the most benefits.
Get More Out of It
Proper foam rolling is going to take more than a couple of minutes. Pick a place on your body that's particularly tight. First step is to roll up and down the tight muscle and determine where the really tights areas are, and generally assign them a "pain level" between 1 and 10.
Roll onto one of the the higher numbered areas and hold. This is where some deep breathing techniques can come in handy (and for me, pounding fists on the ground). Try to breath out and relax into the knot or tight spot. When the number has come down about 3-4 points, roll to the next spot and repeat. You'll find that your muscles will learn to release faster and faster as you get used to doing this.
Generally, it's your first time doing this, you'll want to start with a softer roller (usually white foam rollers), then move to the tougher ones (usually the black foam rollers). If you're ready for some real work you can get one with a PVC core. I've seen these with various diameters and foam thickness to really pin point where you need work done.
Another option to hit smaller muscles, is to use a lacrosse ball or two lacrosse balls taped together:
My janky taping job of lacrosse balls.
You use these in basically the same way, but these are really great for those hard to reach knots in your traps, under your scapula, and in deep in the spinal erectors.