In your folder, ...\Altium Designer 6\Templates, there are various PCBDOC files with letters in front of the names like A4.PCBDOC, B.PCBDOC, etc. Those are template files for title blocks and page index letters and numbers, and the letters in the filename are standard sheet sizes. Open the desired template in Altium Designer, select all, and copy. Now open your PCB and paste the template onto whatever layer you want. Generally, AD uses mechanical layer 16 for this purpose.
There's info starting on page 5 of "TU0110 Preparing the Board for Design Transfer.pdf" which is in your "Help" folder.