Watch the Csus2 (CGDGCD) online guitar lesson by Vicki Genfan from Open Tuning Handbook: Rhythm
This is another tuning that has no 3rd in it, hence the feeling of suspension. We can call this Csus2, the 2 being the note D. It can also be referred to as a 9. Some things are a bit confusing when it comes to naming chords. Sorry. The low C makes this tuning very full sounding, but you may find that your 6th string becomes a little loose. It's OK – just be aware of it and you may choose not to hit the string quite so hard. I use medium gauge strings and that makes it easier to handle the lower tunings (13-56). However, for now you'll probably be using light strings since that makes playing easier overall. If you decide to use open tunings often, or if you keep one guitar in open tunings and another in standard, you can experiment with different string gauges. You can even just replace your 6th string.
In the Level 1 & 2 exercises for this tuning, we'll play the I-vi-ii-V chords in first position, which are beautiful and feature lots of open strings. In Level 1, we use a new strumming pattern, and in Level 2 we learn the Travis finger picking technique. In the Level 3 exercise, I'll introduce you to some new voicings up in the 7th and 9th frets over a simple "reggae" feel.