The invite page is available to all creators on Patreon. At this time, patrons cannot invite creators from the referral program.
If you are a creator, you can refer other creators by selecting the option to Invite Creators which is accessible via the drop-down in the upper right:
This will bring you to the page where you can invite other creators. You can spread the word by sending a message via Facebook or Twitter, or if you know someone personally you want to refer you can send them an email individually.