How do I edit the header / footer / sidebar area?

From website:
  1. In admin menu, click on 'Areas'. (Make sure you are logged in as admin before you go to the website)
  2. Green buttons will appear in the screen. Press on the area you wish to edit
From Admin:
  1. Go to "Areas" section, which appears in the sub-menu that is shown when pressing the Cog icon on the top menu 
  2. Press on the name of the area that you wish to edit, or it's "Edit" action button
  3. Make the changes that you want.