Some vocabulary info would help. As a beginner, words like "hatha" and "ashtanga" mean nothing, so hard to select.
According to Wikipedia:
* Hatha is seems to be a branch of Yoga (Hatha apparently means "force")
* Ashtanga is another type of Yoga brought to the modern world by Sri K. Pattabhi Jois and involves synchronizing breath with a series of positions.