This article will take you through adding Deal Financing to a Customer Order > Unit Deal
We would recommend that you setup the Customer Order > Unit Deal and then add the financing
To add the Deal Financing to the Customer Order > Unit Deal - Click 
Then the user would need to select the relevant Finance Provider and then complete the relevant fields
If your Finance Provider is not listing for selection, then the user will need to ensure that the relevant Vendor has been setup as a Finance Provider
This needs to be only done once and then the Finance Provider will be available across all CO at all times