First, your fitness center SHOULD have some foam rollers lying around. Usually in the functional training room or some kind of stretching area. They are typically long black styrofoam pads. Although they do come in multiple different sizes and materials. My personal one is made by Trigger Point and is about a foot long. It's basically a pvc pipe with a pad around it in all honesty haha.
Now that you're carrying around this crazy thing, get ready for a little discomfort and probably some eyes checking to see what it is that you're doing. Don't worry! I foam roll EVERY day. No exceptions, it is in my opinion the best thing for your muscles. Other than an actual massage from a licensed therapist of course. They way I use a foam roller is I will roll whatever muscle group I am working out that day. Today for example was leg day. So I rolled my glutes, hamstrings, quads, and calves. As well as what I trained yesterday, which was back. So I hit my lats with some SMR for recovery. How to use the roller is actually pretty simple, you just lay on it and roll your body over it over and over. Your quads for example, you are going to want to lay on the roller just below your hip bone. Almost like you are planking on it. The only thing touching the floor however should be the roller and your hands or forearms, depending on what you prefer. From this point you're going to walk your hands forward, letting the roller roll down towards your knee. Just go about 4 inches at a time! Think origin and insertion of the muscle, or to make it easier, ill say the top and the bottom of the muscle. Back on the quads, just roll the top 4 or so inches and then take the roller to just about the knee and to the bottom 4 or so inches. THEN you can roll the entire length of the muscle. This is especially true with the IT Band, don't just start rolling the entire outside of your leg at one time, this will be very painful and could cause some injury. So its like this: roll the top, roll the bottom, then roll the entire muscle nice and slow. Should be about 60 seconds each muscle, or longer depending on how bad off you are haha.
You are looking for knots. They will feel like bruises, try and roll those "bruises" out as much as you can and then move on to the next muscle group. Rolling these knots is basically like massaging them away. Making you able to move much more freely, thus helping to avoid any injury. Not only will SMR help keep you injury free and nice and flexible, it will also aid in muscle recovery. If you are a seasoned SMR vet, then you are most likely using lacrosse balls or kettle bells as your foam roller. As always, please feel free to ask me any questions you may have. Happy rolling! :)