How do I edit a doc

You can't in Adobe Reader on an iPad or iPhone. Likewise, you wouldn't be able to edit in Reader in Windows or on a Macintosh.

Adobe Reader is a FREE app for READING PDFs. If you want to edit a PDF, you need to BUY an application like Adobe Acrobat, available for Macintosh or Windows computers.

Another option is to subscribe to the ExportPDF online service and convert the PDF to an editable format like Word. Here is a quick tutorial on How to convert PDF files to Word or Excel with Adobe Reader Mobile for iOS