You can only report people who have sent you an inquiry or received an inquiry from you.
If you wish to report someone who sent you an inquiry, follow this link to the Leads Received page. Find the inquiry they sent you and click on the row. This takes you to the detail page for the inquiry. Click on the Report Abuse button, complete the form, and click on the Submit Report button.
If you wish to report someone who received an inquiry from you, follow this link to the Inquiries Sent page. Find the inquiry you sent and click on the row. This takes you to the detail page for the inquiry. Click on the Report Abuse button, complete the form, and click on the Submit Report button.