Go to the File menu then down to Export.
Choose your Adobe PDF Preset: Press Quality, this will make most of the settings for you.
In the list on the left hand column click on Marks and Bleeds.
Make sure that the Printers Marks are clicked on and that you have at least a 2mm bleed. 3mm bleed is even better.
Now save your PDF file as something sensible such as "My Artwork Output for Print.pdf"
Navigate to our upload page and follow the simple instructions