If by Adobe you mean an Acrobat .pdf, you won't be able to edit it directly (that's one of the reasons people use Acrobat).
The Acrobat reader that most people have installed is just that, a reader. Having said that you can usually cut and paste the information from .pdfs into something else (although the authors sometimes block this as well).
The normal way of editing Acrobat documents is to use the original source of the .pdf and the full version of Acrobat (not cheap) see click here
short answer : You can't (not unless you have the full program; and you'll know if you do because it will have cost you at least £100 (£200?). Adobe Acrobat (or either of those names on its own) is just a reader - as Batch says.
pdf995 - its free and has pdf writing and edit software for download.
The 995 refers to the price (in $) if you decide you want some additional bells and whistles - like getting rid of some ads - when being used it requests IE to go to their website, but all you do is cancel - works very well
This thread is now locked and can not be replied to.