Everything you write is a page. Some pages are grouped into collections. A collection is what most tools call a blog.
Making one
New page asks for a title. The address is made from the title. You can change it before or after.
Each page has a title, an address, and an optional excerpt. The excerpt is the short line shown when the page is listed or shared.
Collections
A collection is a named, ordered group of pages. You can place a collection on any page, and it shows as a list that updates itself as you add to it.
For example: write three pieces about moving Shopify themes, put them in a collection, and place the collection on your front page.
Your front page
One page is the one people land on at your address. Everything else is reached from it: through your menu, through a collection you placed, or through a link you send.
Importing
Import HTML takes a page you have elsewhere and pulls the text in. Formatting that has no place here is dropped.