In the command hub section of your website, click on Add page button
Then select Custom pages and click NEXT
Then click on the Page Designer button
In the Page Designer window, select the tab you want to start with, like for example content, then select a content layout you want and click on it and it will automatically be inserted on the left side window. The left side panel is a preview on how the arrangement of your site will look like, you can go and select other tabs like header, footer or contacts and simply select a template, once you are done simply click the save button in the bottom right.
Then you will see the page editor window again, click on the Unlock Code Editor button
Then select Yes I know what I'm Doing button.
Then you will notice the page designer button will change to Inline Editor, click on it.
You can edit your website directly from the webpage :), simply click on the image or text you want to edit and select the edit button to change it. once you are done editing it, click the Save button located at the bottom right corner of your screen