Can't Edit a PDF in Acrobat X Pro

Hi! I am BRAND new to Acrobat. I bought Acrobat X Pro and I am trying to edit an existing PDF form (which I didn't create).  I watched the tutorials and I am able to bring it over to Acrobat but I can't edit it.  There is only a FORMS option to the upper right hand side.  Where are the Tools, Comment and Share menus that I see on the Abode TV videos?  Can someone please help me out? I have about 8 of these pdf forms that I need to edit.