Thanks for wanting to be a part of the Know Community. We need to quickly review your profile. Until you are approved your ability to view and post content as well as connect with groups and other members will be limited.
The "Invites" section displays all the invites that you have sent and are pending to be accepted or rejected; that's why it is empty. In order to invite a person, you need to use the "Invite" button at the top of the page (below the cover photo).