Attach it to the camera and half press the shutter button (like, to focus on something). You should hear the AF focusing. Then, with it held half-pressed, make gentle circles in the air with the lens. You should feel it pulling against you and hear a gentle whirring sound.
thanks for the advice. how can I tell if the IS works? why would it not be working?
and I have no idea what this means!
Also, if you don't know, the EF system is for full frame as well as APSc