edit new or existing post with tgdiv

i understand how to set a global post/page template and i understand how to create a cloud or blank single page/post but i can’t figure out how to edit an existing page/posts’s content or post new content to the page with tagdiv! any page or post i open is wordpress and i see no option to edit with tagdiv. for example: if i want to edit one of the MANY pre-set demo pages that came with the theme (ie pages linked to homepage that came wiith pre-existing fake content) how do i change the fake articles into real ones??

i just opened one of these pre-existing pages and had to alter all of the text and photos deleting one block at a time and adding my own using wordpress because i can’t figure out how to do it with tagdiv.

with wordpress i was unable to customize the pull quotes or layout etc.
all of the tutorials say you can create a custom template and they all show how but not a single one tells you how to open an existing page and edit with tagdiv instead of wordpress. thank you.