Click the requested standard below "Answer".

Now, you can either choose an existing certificate that has been uploaded previously or (most likely) you will have to upload a new certificate. For the latter, click the "Create a new one" button.

Follow the steps as described. Click "Continue" and upload the certificate itself. Lastly, provide all certificate data including the issue/expiration date, document/license number, issuing body and any additional remarks (optional). Confirm by clicking "Request".

After creation, finalize the submission by clicking "Save".