Key signature
Total 15 key signatures - C major has no flats and sharps so not count here
F C G D A E B
B E A D G C F
Flat key signatures is the backward of sharp key signatures
Scale
Major: W W H W W W H
Minor: 3 half steps from major scale, and play same notes (same formula) as major scale.
Circle of fifth
Write about this later. It is an important concept in constructing chords.
Pieces beginner should play
Prelude in C major by J.S. Bach