I did a search for lawn mower manuals and found this site:
Now, you might find (as I did) that most of them look about the same, regardless of exact model.
Before you start, lower the mower deck to the lowest position it will go. This will give you clearance to work. Some models have a special service position that is lower than the normal cutting range.
It is highly likely that the pulleys have guards / covers over them that must be removed with a small wrench. Make your life easy and spray them down with liquid wrench, WD-40, or some kind of solvent to loosen the bolts before you start scraping up your knuckles.
Look at the two pictures I have placed below. They are from two different manuals for two different lawn mowers and, other than the angle and the amount of detail, they are just about the same. Notice the covers over the pulleys have already been removed for easy access.
I lost my pictures; still new at this. Let me try this again.