Mark, your drawing is not correct.
See below, what it should look like (simplified drawing.. . the more accurate drawing from the geometrical optic point of view can be seen here (picture is from Wikipedia) :
http://upload.wikimedia.org/wikipedi...-Lens3.svg.png))
webpage:
http://en.wikipedia.org/wiki/Lens_%28optics%29
The focal plane is presented with the vertical line on the right, focal length is the distance between the focal plane and the lens.
I found interesting applet that will give you even better insight as to what is going on here (it came from
http://phet.colorado.edu/en/simulation/geometric-optics
http://phet.colorado.edu/sims/geomet...optics_en.html
Choose principal rays to see the same geometrical construction as on wiki page