Editing YAML Front Matter from Admin Panel

I'm new to Grav, so I hope my question makes sense.

As I am learning to construct pages for a site, I am unsure about whether I can construct new pages entirely from the Admin panel by assembling the modular pages from the theme's templates, or if I need to make some of the modifications from my ftp program as well. For example, I see the styles are set up for the modular pages in the Bones demo site, but I can't find where I would edit those styles from the Admin panel.

Here is an example of what I mean by the styles in the Front Matter, in the Header portion of the Typography page in the Bones theme:
2016-08-12_20-32-19

Is there a way to change for example the blue color from the Admin Panel?

Also, any direction as to where I might find further reading on this would be great. The Learn docs are good, but I'm just missing a few insights like this one that I'm posting. :)

Thanks!

First, if you are developing a site, you should really do it locally, then push the final site to your 'live server'. This is a much more efficient way to develop. See my blog post on the subject

Second, as a web developer, you will be more productive if you work with the files directly (this is another reason why working locally is better). Grav is a flat-file system, so 100% of things are editable via the files, while probably 90% is available via the admin (and even then with some restrictions). The admin is primarily intended for on-going content creation and maintenance. It' snot intended for the initial development. While possible, it really is going to make things harder compared to editing directly. The docs are definitely 'direct file access' focused.

Thank you so much for your prompt reply. :) This is exactly the kind of information I am looking for, as I am researching a way for writers (end users) to implement Grav for their website and blogging platforms.
Approaching the development by editing the files directly makes sense, but I wanted to be sure I was approaching this as it is intended to be managed.
The templates are amazing, and the file arrangement is not terribly difficult to understand, which is why Grav has been the first candidate for my investigation.
And so far, the technical support has been outstanding as well. ;)