knife subdividing?

can someone explain exactly what i must do by the following line:extrude and subdivide (using knife tool) the plane in side view and convert to subsurf of level one to make it look like this:
i just don’t have a clue.

1: select the plane
2: press Ekey… extrude (in the direction of the result needed).
3: press Kkey -> select knife tool … this cuts the plane up …
4: Get out of Edit mode by using TAB key …
5: Go to Edit section by using F9…
6: Press SUBSURF button whilst making sure SUBDIV is set to 1

Clear enough I hope ?