THose are the rubber band type, as they are commonly referred to. Most of those types have a couple of "pins" at the end of them that attach to the opposite end to make a loop. To attach them together, heat a small screwdriver with a lighter until fairly hot, then touch the tip to the pins once assembled, mushrooming the pins out a bit. This will hold them together.
Unfortunately, most of those type of tracks are not very flexible, but when put on the wheels, they will conform to the shape of the actual tread. They are alot easier than individual tracks, I assure you. Take it from someone who has done several of both.
If you have any more questions, feel free to ask away.
demono69