For those that don't understand what he means by "count backwards", this is how you find all the keys in a scale
say you want to find
the G major scale, you start at the G key and count "whole whole half whole whole whole half", that's the formula for finding the major scale.
So start at G, move up one whole, which is A, another whole, which is B, then move up a half which is C ( note: E to F, and B to C are considered moving up a half ), nove move up three wholes, D, E, F, then move up a half, which is F#
so it would be
G, A, B, C, D, E, F, F#
and if you want the minor scale, you flatten the 3rd, 6th, and 7th, note like the Op said.
I'm also learning this, and to me it's not too difficult, i'm trying to learn chord progressions which is a little bit more difficult.