I cannot edit a pdf document. I am using Acrobat Pro DC. I follow the directions and click on the edit pane but nothing happens.

I cannot edit a pdf document.  I am using Acrobat Pro DC.  I followed the directions in the tutorial but they don't work.  I click on the pane Edit pane on the right side of the screen but nothing happens as it does in the tutorial.  No tool icons or format icons appear.  What do I need to do?