Good question! I've managed to pick it all up through various Wikipedia pages and journal articles on programming language theory and type theory. There's probably some good books and/or review articles that could take you through all of the foundations, but I don't know what they are.
All you really need to understand, though, is the syntax for describing syntax, small step semantics, and big step semantics, and what those mean. If you go back to the previous post on the UCC, I try to explain each of those in the context of that calculus. If you have any specific questions about things you find confusing or opaque, I'd be happy to answer them.
It might also help to read the source code for UCC and UMCC, if you're more familiar with code. But code tends to be much lower level, where it can be difficult to see the forest through the trees.
All you really need to understand, though, is the syntax for describing syntax, small step semantics, and big step semantics, and what those mean. If you go back to the previous post on the UCC, I try to explain each of those in the context of that calculus. If you have any specific questions about things you find confusing or opaque, I'd be happy to answer them.
It might also help to read the source code for UCC and UMCC, if you're more familiar with code. But code tends to be much lower level, where it can be difficult to see the forest through the trees.