A suspended chord (or a chord suspension) is usually made by holding one of the tones of a chord a tone higher, then resolving it to its resting place. This can be done with any tones of a chord, but one of the more common suspensions is to manipulate the third of the chord, by first playing the fourth, and resolving it to the third. So a C suspended chord has the tones of the root, the fourth and the fifth:
A C suspended chord of this type is often shown in chord charts as either a "Csus", or a "C sus4". "Sus4" means that the third is initially played as a fourth, and resolved to a third.
In "real music", let's suppose you're playing a simple tune which uses three chords, C, F, and G, then returning to C. Try adding a little flavor to the mix: turn that final chord into two chords. Make it a suspended C chord, followed by a C chord.. Your chord progression would look like this: C - F - G - Csus - C. You can try this on a guitar or a piano.
Experiment with other suspended chords. Put them in places where you need a bit of emotion in your music. Might be just what you're looking for. Take a Christmas carol book (one that has chord symbols in it is good for this purpose), and try adding suspensions to dominant or tonic triads.
In the Key of C:
Sus 4 chords- Formed by raising the 3rd of the chord you are playing by a half step.
C-E-G is your basic major triad C chord. The E in bold is your 3rd.
C-F-G: The F in bold is your suspended 4th. Notice that the distance between E to F is a half step. This chord now becomes your suspended 4th chord. If you play a I IV V progression, the IV is the best chord to play as a suspended 4th.
Sus 2 chords- Formed by lowering the 3rd of the chord you are playing by a whole step.C-E-G This is your basic major triad C. The E in bold is your 3rd.
C-D-G The D in bold is your suspended 2nd. Notice that the distance between E to D is a whole step. This chord now becomes your suspended 2nd chord. I hope this helps!