I am building a Pool cabana. I am going to install a toilet.
I will be poring a slab I need to rough in a toilet and sink drain

I would go to Home Depot and pick up a Plumbing book for $10-$15. It will answer a multitude of questions, and you will always have it for future reference and to loan out to your friends. When I built my garage addition, I also purchased a book on Masonry and Home Wiring. They not only provided great guidance, but enabled me to ask pertinent questions of experts in those trades. Good luck.