How do I access the faces of the Subsurf modifier? Changing the cube into a subdivision surface thingy is what I need to do for the model I am making. However when I try to use edit mode, graphing and faces on the subdivided cube it doesn't register the faces of the subdivision object and instead uses the old cube surface Like below



Is there a shortcut or something to fix this or do I need to turn on a setting or what? Please help.
I needed to hit Apply in the modifier settings in order to get faces of the subdivided cube editable in Edit mode.