If you are learning Chinese, you will find that the Conversations and Texts presume you know some basic Chinese words (as found in any small Chinese-English dictionary), but are suitable for intermediate learners for self study.
Learn the vocab first and then study the materials. In the notes there are links to other examples of the language patterns that come up.
It is worth spending some time considering how you are going to get the best out of the materials.
Keep a list of anything you don't understand, in the hope that you will meet someone who will be able to give you an explanation.
In addition to the method outlined above, try changing the situations and adding vocabulary. Encourage role play in small groups and adlibbing.