Once i logged in to my GCKey account i clicked on link my application and then i follow this steps:
Category : Permanent Residence
Sub-Category : Family Class (spouses)
I used the Application number and Family name option (application# and family name for the principal applicant) .
and then i entered place of birth details for the principal applicant ( city and country of birth)
then i entered where the principal applicant intend to live in Canada as i entered in my forms (province,city ) and current marital status in my case is "married".
Finally , i chose number of applicants that are part of this application as 2 (i.e the principal applicant and the sponsor). this is the tricky part i guess i count my self (sponsor) as part of the application.
i hit search for my application and i found it.
you can try 5 times every day
Good Luck!!!