I am a Christian.  Is it appropriate for me to do this meditation and yoga?

This is an extremely important question, and one that deserves significant prayer and thought.  Certainly what we do in terms of our minds, hearts, and bodies matters a great deal to God and can influence us powerfully either toward or away from God.  Ultimately I believe a person should choose to do or not to do based on their conscience, provided they have an understanding of the Bible and its core teachings.  One needs to do what they feel is right;  no one else can tell you what is right for you.  I believe that is why God sent us the Holy Spirit, to live inside of us and help us discern what is right and edifies our bodies, minds, and hearts toward Him.  Ultimately we answer for our actions and beliefs to God alone.  We will have to give an account.