The chord symbol for a suspended chord is the major chord symbol plus the word sus (or sometimes sus4). The suspended chord is quite often used to add interest to a progression if there is a long section of music containing only one chord.
Dsus
Hold a D major chord shape then place your fourth finger on the third fret of the 1st string.
The pale green circle on the chord diagram indicates that you hold the major chord shape and add the suspended note with your fourth finger. Suspended chords are nearly always played just before or just after the major chord so it is easier to change between them if the major chord shape is held in position.
Rhythm Pattern
Asus
Hold an A major chord shape then place your fourth finger on the third fret of the 2nd string.
Rhythm Pattern
Esus
Hold an E major chord shape then place your fourth finger on the second fret of the 3rd string.
The following progression is two bars long. Change to the E sus chord (i.e., add your fourth finger) on the "+" after the 3 count.
Rhythm Pattern
The next progression contains all three sus chords introduced so far. Change to the sus chord on the "+" after the 2 count. Use pivot and slide fingers wherever possible between chord changes.
Rhythm Pattern