Dr Joe instructs people to practice his meditations in an upright position, unless you are an advanced student, meaning you have been to an Advanced Retreat. For more information about why it is important to start meditating sitting up, please watch the video above.
In Dr Joe's book, You are the Placebo (Page 269), he describes how to position your body while meditating. Below is the link to the You are the Placebo book:
You Are the Placebo Book (Paperback)