Hi Richard, just checked your Profile and it shows you are on a Guest Membership and won't be able to use GEDCOMpare to bring your data into WikiTree until you have agreed to be a Volunteer and the Honor Code.
Gilly Wood, who is a Greeter, left a message on your Profile page to help you get started on WikiTree. Please contact her and she will be more than willing to help in this regard.
And Welcome to WikiTree while we're at it.