Here are your major chords in the root position. THERE ARE ONLY TWELVE so don't get stressed! See them as pictures rather than the names as they are easier to remember:
The first three are similar as they are white, white, white
C - C E G
G - C B D
F - F A C
The next three are similar as they are white, black, white
E - E G# B
A - A C# E
The next three are related to the last three. The colours are opposite of them, black, white and black
Db - Db F Ab
Eb - Eb G Bb
Ab - Ab C Eb
Only three to go. Next we have the B's (buzz). They differ in that the colors of the two top notes are the same but opposite of the bottom note (confused yet?)
B - B D# F#
Bb - Bb D FD - D F# A
Wow! the last one. Gb is opposite of G. Black, black, black.
Gb - Gb Bb Db
Now that's all there is to it!!
I suggest that after reviewing them, practice them around the clock (counterclockwise). Here is the clock (the circle of fifths but in reverse, which is the way our music generally moves and is pleasant to the listener):
Practice them with your left hand first as that is where you'll first use will be.
MINOR -Once you have these under your belt, all you need to do is lower the middle note one step ( a semi-tone) to make it minor. Practice this group around the clock (still counterclockwise).
7ths - This is an additional note to either the major or minor chord. It is located 2 steps (semi-tones) beneath the name of the chord or it's octave. Practice this group, both MA and mi around the clock and you will soon the comfortable playing these whenever called upon to do so.