The router is an 8 amp Craftsman fixed base Super Router model # 315.17390. Routers are used to add decorative elements to the edges of wood, to create dados and slots, to make a rough-cut piece flush to another, and to engrave signs. They can also be used to make box, dovetail, and many other types of joints.
One of the most common router applications is to simply round over or chamfer the edge of a piece of wood in a more efficient and consistent manner than sanding alone would allow. There are several router bits available in the woodshop, but more specialized bits can be purchased from most hardware stores, Lee Valley, Busy Bee, etc.
Routers may seem less dangerous than saws with large spinning blades, but the incredible speed they turn at mean they are capable of grabbing your work and pulling your hands where they shouldn't go. They can also fling chips and broken router bits at high speed. Remember your safety glasses!
Unplug the router. The original collet wrench is no longer with us, but there is just barely room for an adjustable wrench to loosen the collet. You'll have to hold down the spindle lock lever while you do this. Replace the bit and retighten the collet.
This manual is for a similar model (note: the spindle lock is very different).