What is Chess Mentor and why this new forum?

Given as the problems range from 800's to 2200's (appx.), I do not think it is specifically geared toward players with little experience.
where can i report a mistake in a chess lesson. I found a mistake in capablanca-Lasker, Berlin 1914-Advanced tactics. in the 4th or 5th move of the lesson it says that Kc6 is an innacuracy whenafter ...Ka8, white doesn't have to move his king foward to Kc7, white can instead push the pawn with c7 where the black king has to move to Ka7