Click "Content" (found at the top of the page directly under the Site Builder banner).
Under "Manage Content" locate the correct directory under "Select Section".
Under "Manage Section Content, Published Content" find the page you want to edit.
See Content Permissions for information on how to gain access to content.
Click "Edit" (found to the right of the file name).
The "Manage Content, Edit Content"window will open.
Edit your content as needed. Once you have finished click "Publish" or "Save Draft".
For more information on "Save Draft', "Publish" and "Quick Publish" see Save draft, quick publish and auto save.