If you have the software there are instructional documents that come with it on the CD. There is a 145 page PDF file. You may be able to download it from the website.
I have been using HAP for more than 7 years, and have faith in it.
Waht i suggest you is that rather than reading a practical example, i send you a HAP project archived file (.E3A) which you can retreive into Your HAP program and there you can see all the spaces, systems and plants that are designed. You can explore the inputs / outputs of different kinds. If you want, i can send you projects of more kinds w.r.t. applications. and if you have some questions for clarification, dont hesitate to come back to me.