@dxfan227 you’ve got it!
You can use almost any word for the titleClass providing you use the same value in the custom.css file. e.g. titleClass: "word" and div.module.calendar td.word - it is possible to include uppercase and lowercase letters (a-z or A-Z) in the word as well as numbers (0-9) or even hyphens (-) and underscores (_), but avoid punctuation and other such characters. There are many recommendations for css class naming conventions, but that’s for another day. I’d say just be clear and descriptive.
The color is defines by the hex value (e.g. #0e66b3) . Here is an overview if you’re not already familiar - https://www.w3schools.com/cssref/css_colors.asp
It’s worth noting the css is defined in the custom.css file. You may find some suggest changing the files within the module directory. Avoid this where ever possible as such changes will make updating modules more difficult.
Remember this customisation is only required because it can’t currently be achieved using the calendar modules configuration options. It’s possible (but less likely) that future changes to the module may break these customisations so watch out if upgrading the mirror.
As you learn you may wish to push changes to the modules code so they become supported configuration options for others to use.
Take it slowly, and enjoy the mirror.