When you open the theme editor, your store's home page loads by default. You can use the dropdown menu to select a different template or use the search bar in the template dropdown to search for a specific page type. Selecting a template loads it into the theme editor, and any changes you make are previewed in the editor as you make them.
If your screen is wider than 1600 pixels, then your customization and editing options appear
on the right side of your screen. If your screen is smaller than 1600 pixels,
then they appear on the left side.