Once you logged in to the Identity Server, you can upload the public certificates of the trusted relying parties.
1. Sign in to the Identity Server Management Console as described here.
2. Select "Trusted Relying Parties" under the "My Identity."
3. Click on the "Browse" button to upload a new relying party certificate to trust.
4. Select the certificate from the local files and click on the "Upload" button.
5. The relying party certificate will be displayed in the "Personal trusted relying parties" pane.