If the PDF is not locked, you can add fillable boxes. I don't have your version of Adobe but down the left hand edge of my version there is a symbol that looks like a document with dotted lines that start at bottom left and at top right. They meet at bottom right forming somewhat of a plus sign. Click on this and basically draw a box where you want to enter info. Once box is drawn, a dialog box opens when you select font, size, etc.
Hope this helps.
I have Adobe Acrobat 6.0 Pro and have received a PDF file that is not fillable (and apparently not protected.) Is there a way to change this file so that I can type in my responses?