Hello, and welcome back to a new instructable, the K'nex Bow(or whatever you want to call it)!
Step 1: Shape
Connect the two yellow rods to the light gray connector to create the picture above.
Step 2: What Makes This Shoot
Place a rubber band over the shape.
Step 3: Ammunition
Here are a few of the many types of rod-only ammunition (of course, there's more).