You can't do that with Adobe Reader, you need to have Adobe Acrobat to edit PDF files.
With Adobe Reader you can only view, fill form fields, sign and add comments to a PDF. Take a look at Adobe Reader XI/Features and http://helpx.adobe.com/reader.html.
With Adobe Acrobat you can:
Create PDF files
Merge and combine files
Simplify reviews and approvals
Protect PDF files
Prepare files consistently
Convert PDFs to other formats
Edit PDF documents
Create and analyze forms
Take a look at this link to know what you can do with Acrobat: http://www.adobe.com/products/acrobat/product-comparison.html