You may have noticed that playing one key at a time doesn't really sound like...well.. "lots of music". Musicians call that "full-sounding". And I'm sure you've tried to play more than one key at a time, with only moderate success. Some of them sound OK, but lots of them sound, well, terrible. Obviously some keys go together, and some just plain don't. The question is, how do you know which ones will sound ok and which won't? Isn't there some simple way that works all the time?
(Boy, you'd be disappointed if I said "no"...)
...but fortunately, the answer is "Yes!" and you won't believe just how simple it is.
  To make a major chord of three keys, start with whatever key
you like (called the "root") then SKIP OVER THE NEXT
THREE KEYS, and play the 4th key. Then SKIP over the
NEXT TWO keys and play the third.
That's it!
So, if you start with "C" with your thumb (1) on the right hand , then skip three keys, (remember to count the black keys too) the next key is "E".
Press it with your middle finger (3).
Now skip the next two keys, and press down the one after that, the "G" key with your pinkey (5).
Now play all three keys at the same time. TA-DA! You have just done a 3-key chord.
So once again, here's the rule, no matter WHERE you start:
  SKIP 3, SKIP 2 MAKES A MAJOR CHORD.
Now, get this: nothing says you have to press those three
keys all at the same time OR even in that same order!
Try pressing first "E", then "G" then "C".
Try "G" twice, "E" twice, then "C", "E", "C".
Mess around.
There isn't anything you can do using those three notes which will sound wrong : NOTHING!
(You may like some patterns better than others, and that's great: it means you just invented YOUR OWN MUSIC!)
Try the same keys in a different octave.
Try the three keys in TWO octaves.
Try pressing one key, then the other two together.
Whew! I'm running out of ideas: YOU think 'em up, and have fun!
............(waiting while you play)............
Now for some names:
Whatever key you start on, using the method above, is called the "root" key.
The key you hit after skipping three is called "the third" (convenient, isn't it?)
and the one you hit after skipping two more is called "the fifth" (as in 3 + 2 = 5).
And, with the "C" chord we used fingers 1,3,and 5. (Doesn't that work out nicely?)
Oh boy, now we really get to sound like we know what we're talking about...
that a major chord is composed of a root, the third and
the fifth." (Try to do this without smiling or you'll never
get away with it...and for heavens sake, don't let them
know how simple it really is!)
At first, you'll probably have to actually count the notes, but you'll find it doesn't take very long before you can just "see" three to skip and two to skip.
If you want to quit and just play with making major chords for a while, that's fine. Nothing says you have to read this whole thing in one sitting; and there's a very good chance I'll still be here when you start reading again. Have a good time. (and remember there's more than just the "C" chord...you can start anywhere. Just skip three and then skip two.)