Youre almost there. You have the tracks and the wheels. For the animation you need to do three things:
insert keyframes for the big wheel to rotate. (select place on timeline, rotate wheel, press i -> rotation)
add constraint for the tracks (select tracks, add constraint of “transform” type, select the big wheel as target, and map the Y rotation of 0 to 360 degrees into an x translation of (2PIbigwheelradius)
add constraint for the small wheels, to make them rotate based on the big wheels rotation.
And here’s a bit of advice for asking help on the blenderartists forum: Many people are willing to give advice/help on how to do something. Just a few are willing to do something for you. So even if you are very limited in your time, it is better to ask “how can I do this…” than “Can you do this for me?”. You’ll not only get a reply sooner, but you’ ll also learn more out of it.
On second look I notice that that the pulleys do have a wire material set so they would be seen rotating in an animation. I aint going there. Look back at jonim8or’s suggestions if you want to do that.
EDIT: Because I’d never done it before, I went back and did the pulley rotation. I also looked at the original model and the proximity of the belt to the small pins, and realized you probably didn’t want it tightened.