Blazonco

Step 1
Click CONTENT from the primary navigation tab.

Step 2
Click the Page you want the new page to appear under.

Step 3
Once selected, click "Create Page" button in the upper right corner of your content tree column

Step 4 
The Page Properties will appear to the right. Type the title of your new page. Select a Navigation option.
"Do not show in Navigation" - page will appear in website editor but is hidden on the live website
"Show in section navigation" - page will appear as a drop-down within which ever page you selected it to appear under
"Show in top-level nagivation" - page will appear as a main tab on your primary navigation

Step 5
Click Create Page

Step 6
Select the newly created page from the content-tree from the left menu. The page properties will appear to the right. Select the "master page" that you want for styling. Usually the "default" is a good choice. 

Step 7
Click "Save". Page is now ready to add content. Click the pencil to the right of the page from the page manager tree to edit and begin adding content.