Try installing the Flexibility Extra. It wasn't until I had a full working site to play around with and "see" the TV's, snippets, and chunks actually functioning that I found myself with much working understanding. I'd mucked about with the MODX Boilerplate prior to that, but the TV's still had me confused and I couldn't specify parameters in a snippet call to save my life.
Actually, the video tutorials at
Design From Within were in fact... prior to the first Flexibility package release, what really did the trick for the basics (working with MODX Boilerplate). Being able to play with a working site with Flexibility afterwards allowed many ahh ha! moments to move forward with.
Flexibility is not extra comprehensive, but it contains all the basics such as a working Wayfinder menu, various getResources calls dependent on TV values, MIGX based slider, custom TV output with the Switch snippet, static resources, a gallery, contact form, jquery lightbox, search with results page, etc. At the moment, it's missing some biggies like Articles and a calendar, but you'll figure those out. The best part is that it's a fully functional responsive grid based on Foundation which is super slick IMO.
I would suggest that you first download Flexibility 2 first (the package just prior to V3.0) because the dropdown menu in V3.0 is giving me fits at the moment, and I know it works nicely in 2.1.1 .
You can get prior versions at GitHub.
2.1.1 is here 2.1.1 uses Foundation2, while Flexibility 3.0 uses Foundation3 (different, yet the same in many ways). To see what that means, enjoy the
Foundation site