Tinny, if the flightpath is angled up at say 5 degrees in a climb, then some of the lift from the wing acts backwards. In the US, we call that the rearward component of lift, and it adds a little to the total drag from induced and parasite drag.
In anything except level flight, lift can be resolved into a vertical component (=weight in unaccelerated flight) and a component acting forwards (descent) or backwards (climb).
I hear ya about diagrams ...