Upload Tab page is shown as follow.
For uploading, first you need to click to select a certificate from the top left string grid. That string grid is a reflection of MySQL table_cert_list table.
The selected certificate should have its CSR assigned a license before, so its cert_status field should displays as a license number, such as "license1", "license2" etc.
You don't need to create a new certificate file for uploading. You can open an existing certificate from DB (or even to import from a certificate file) into cache, modify the certificate's remote attributes, and then upload them. In the meantime, you can save the modifications back into the DB (i.e. table_cert_list table), for next time work, without the need to create a new certificate file.
The uploaded content is just limited to an certificate identifier plus those remote attributes. The ready-to-upload remote attribute definitions are shown in the middle left GroupBox titled "Verify Assigned Remote-Auth-Attributes Data". Each time before uploading, review this GroupBox content to make sure this is what you wanted to upload.
All passwords or keys etc credential data will not be uploaded and will not transmitting out over network.