It's hard to explain to you right away how to play a particular chord. I myself started learning guitar from scratch without a teacher not so long ago, and I can say that it is not possible to learn chords quickly. And to learn it you need to find a complete guide, which describes step by step all the stages of learning to play the chord Cadd9 on the guitar, such as here
http://play-guitars.com/how-to-play-the-cadd9-chord/.