Beth, in your third to last paragraph of your first post you started to touch on what I’m trying to understand. For example I am using pins D7, D11, D21, and I can refer to them in the code as 7, 11, 21 in basic sketches. But what does scl, sda, on the digital side, or AA1, AA3, etc on the analog side mean and how do I refer to those pins in the code. It sounds like you are saying you will learn what those are as they are used in some tutorials that you find online. There is without a doubt a wealth of information online that continues to broaden my understanding of the subject but that is a tedious way to get answers to specific problems or questions. I was hoping to find more board specific information, like info about working with the 5v booster needed for the HC-SR04 sensor. It seems like you learn about the board through learning about programing vs a more explicit diagram.
Welcome to EnviroDIY, a community for do-it-yourself environmental science and monitoring. EnviroDIY is part of WikiWatershed, an initiative of Stroud Water Research Center designed to help people advance knowledge and stewardship of fresh water. 
