Changing skeleton content

I just downloaded and installed the Ceevee skeleton and added the admin plugin. Now I wish to change the content of the start page. I can see the content, that I want to change, in user/config/site.yaml, but I cannot see it in the admin panel. Am I supposed to change the files rather than editing the content in the panel?

This skeleton probably doesn't have an update site.yaml blueprint that is required for the new fields to show up in the admin. Just change the user/config/site.yaml manually.