With the Certificate Manager, you can upload documents for a contractor yourself if you already have them. Click into the contractor you'd like to upload documents for, then under the Documents section, click "Upload".
First you'll have to select the dates that the document is valid for. Then either drag in your file or click Upload File to select from your own folders. Once you've uploaded the documents, you can view and review the documents. Feel free to upload as many as you'd like!