User Defined Tags, Tags and Modules,
This review is from: CMS Made Simple Development Cookbook (Paperback)
Goldstein takes a lot of the mystery out of programming in CMSMS. With some luck, your needs for a modification of the basic CMSMS package will be readily implementable using tips from the book. As the recipes make clear, all this sits atop PHP code. Knowledge of PHP is a prerequisite for understanding most of the recipes. However, a quick glance at these shows that the PHP code examples are mostly self explanatory in terms of their semantic value, even if you don't know PHP. Which by the way is a good instantiation of why the language has proved so popular.
The other requirement is to understand HTML, since several or many recipes revolve around using PHP to construct HTML snippets. Luckily, here too HTML is a simple language to pick up.
The book divides its recipes into 3 groups - User Defined Tags, Tags and Modules. At the highest level, the most important lesson is which of these you should pick to handle your problem. So pay careful attention to the first chapter, which is essentially a flowchart of how to make that decision.
Of these groups, a module can be the most complex, at least as evidenced by the book's choices of recipes. The modules often tackle processing of data. Here is where the complexity can arise. CMSMS uses a free relational database management system like MySql or PostgreSql. What eventuates is that module coding needs an understanding of SQL grammar. Unfortunately, this can be somewhat verbose, shall we say. But if you plow through the SQL parsing, you can write the appropriate deconstructionist code to get at the various data fields.