Often the first thing a non-photographer will notice about one of our images is the sharp subject in the foreground with a blurry background. If you're shooting with what we call a 'point and shoot' camera it can be difficult to achieve this, but with a dSLR you can create the background blur (called bokeh) quite simply.
If you're just starting out, try your hand with the 'A' mode on your dSLR. That's A for aperture, not auto!
Aperture is how wide the shutter will open when you take a shot. The wider the aperture, the more light that is let into the lens and the shallower your depth of field. A shallow depth of field is what will give you nice smooth bokeh.
The diagram below gives a better illustration of how depth of field works that we can e...