can anyone post the different keys and the major chords that are in them then all the chords in them
like the key of G
C D G three major chords then theres Aminor and F and all that stuff...so can anyone help please?
Use the circle of fifths. The surrounding five chords of a key make up the chords that fit in with that key. Outside ring is major chords inside is minor.

So yes, G has C, D, G, Am, Bm, Em