On a PC (Windows XP):
Press Ctrl + P on the keyboard. When the Print dialog appears, select “Adobe PDF” from the drop-down menu at the top. Name the file whatever you wish and click “Save”.
On Mac:
Press Command (⌘) + P on the keyboard. When the Print dialog appears, click the “PDF” button on the lower left corner and select “Save as PDF…” Name the file whatever you wish and click “Save”.