When the above is not sufficient, the pretext-support Google Group is the right place to ask questions. If you are trying to determine which elements to use to accomplish something, provide some context. Do not ask, “How do I print a line of text upside-down?” Instead say, “I am writing a monograph on mammalian vision, and I'd like the reader to use a mirror to view a line of text written upside down. What is the best way to do that?” (I think the answer would be: make an image and include that, rather than trying to get reflected text.) Sometimes a quick search of the Goggle Group may yield insights.
When you have a question about design, or are pretty sure you have encountered a bug, then the pretext-dev list is the place to start a discussion. As you get more comfortable with PreTeXt this may be a more useful venue for more detailed discussions.