This page is available by selecting Preferences > Default Project Preferences

Vendor name: This field is usually automatically populated by whomever is defined as the licensee in the license. However, this field can be edited. This can be useful if the company preparing the content for submission is aggregating for multiple vendors.
Vendor Description: This field is optional and can be used to write a short description about the vendor.
Vendor URL: The Vendor Website URL can be entered here.
To add a contact, select the Add Contact button and complete the fields accordingly.
Use the Import button to import the values from a previously created CSV file.