Editing Page in SharePoint Designer 2010 with Advance Mode

I have tried to edit a page and got a code that was marked in yellow. In addition, the Ribbon was missing some of the tabs. I was unable to edit the code on the page.

Solution:Click on “Advance Mode” button that is located on the Ribbon.
Once you have clicked it, you’ll see the other tabs and you will be able to edit the page.