switching chords :)

To switch from Em7 to Cadd9 (diagrams below) do the following:

1. Play Em7 with your middle finger on the A string 2nd fret. Strum all the strings.

2. To switch to Cadd9, slide your middle finger up 1 fret to the 3rd fret on the A string.

3. Place your index finger on the 2nd fret of the D string.

4. Place your ring finger on the 3rd fret of the B string.

5. Strum all strings except the low E string to play a Cadd9 chord.

Asaph's answer is perfectly legitimate, but thirds in the lower or bass part of a chord can make things "muddy", so I'd like to provide this alternative:

Ideally, you could finger the chords identically so that you only need to slide one finger to form the new chord.

A popular fingering here is Em7: Index, Middle, Ring/Pinky (on the diagram, from left to right), but you need to "switch places" with two fingers so you end up with Cadd9: Middle, Index, Ring/Pinky.