If I got your question correct, it's more of a DOF (depth of field) thing. To have a shallow DOF, meaning your subject is clear but the background is blur, you open up your aperture. To have a deeper DOF, you can close down your aperture. Hope this helps and here are two websites that may help you.
else u can try with ur kit lens fully zoom out with your aperture at the WIDEST possible setting... focus on something as near as possible... and have some background far away... eg, focus on your window grills... with backgrounds. have fun.