Select the camera and change the blur value to something other than zero (5 is good to start with). You should see an x in front of the camera in most views...this is your focal point (change the value in the focus box to move it forward and back). You should also see 2 square planes within the camera view (one before the x, and one after). This is your blur range...the higher the blur value, the closer the squares get to the x (and the smaller the range before things get really blurry:} I haven't used it much yet, but that should get you started.