This an easy way to learn how to play "Happy Birthday" on the guitar.
There are only three chords that you need to learn for this song. They are the following:
(The chord tabs are laid out in this order of strings | E A D G B E | which means from top string to bottom. The numbers stand for which fret is supposed to be pressed on each string. The 'x' means that the string is to be silent.)
The G Chord:
| 3 2 0 0 0 3 |
Press your middle finger down on the 3rd fret of the top E string, the index finger on the 2nd fret of the A string, and either the ring finger or the pinky on the 3rd fret of the bottom E.
The C Chord:
| 0 3 2 0 1 0 |
Place your ring finger down on the 3rd fret of the A string, middle finger on the 2nd fret of the D string, and the index finger on the B string.
The D Chord:
| x 0 0 2 3 2 |
Place your index finger down on the 2nd fret of the G string, ring finger on the 3rd fret of the B string, and the middle finger on the 2nd fret of the bottom E string.
If you are just starting to learn the guitar, practice holding the shapes of these chords and switching between them so you can be familiar with them. In that way, when it comes to working on strumming, you're not trying to learn both how to change chords and how to strum at the same time.
The easiest way to strum Happy Birthday is to play only down strokes for every beat. The singing will carry the swing of the song, so you do not need to worry about any up strokes. The beat count for the song is in sets of three. Below is a lay out of the count for the song.
Happy 1birth2day 3to 1you 2 3Happy 1birth2day 3to 1you 2
3Happy 1birth2day 3dear 1(name) 2 (pause) 3Happy 1birth2day 3to 1you
The numbers are placed exactly where the down strum should happen in the song. The syllables with a number accompanied with it have a down stroke happening at the same time. For example, a strum happens right on "birth" of "birthday" and also right on "day" of "birthday".
Put Them Together
Now let's put the chords and strum pattern together.
The order of chords is: G - D - G - C - G - D - G.
Here is a lay out of when exactly to play these chords.
Happy Gbirth2day 3to Dyou 2 3Happy 1birth2day 3to Gyou 2
3Happy 1birth2day 3dear C(name) 2 (pause) 3Happy Gbirth2day Dto Gyou
All of the chords except one are played on the '1' beat. The only exception is the last 'D' of the song.
The trickiest part of the song is the quick chord change from 'D' to 'G' right on the "to you" at the end of the song. If you have trouble with that section, practice it slowly, then build up speed.