No worries, a quick summary on ECAS. The first that time CIC contacts someone, they generate a UCI for that individual. That UCI stays with them through all future applications. In my case, in 2010 I applied for a working holiday visa and I still use the same UCI today.
So, as the sponsor this was probably your first time dealing with CIC (unless you emigrated to Canada or what have you). So, assuming this is your first experience with CIC when you received sponsor approval letter that would have been the first reference to your UCI. During the sponsor approval process they would have added your husband to their system, and this step would have generated a UCI for your husband, but you do not know it as they most likely have not sent your husband any communication yet.
So, there are 3 ways to use ECAS.
1. Using the sponsor's UCI (located above the file number in the sponsor approval document) and the sponsor's family name, date of birth and country of birth.
2. Using the applicant's UCI and the applicant's family name, date of birth and country of birth.
3. Using the file number (located under the sponsor's UCI in the sponsor approval document) and either the sponsor's or applicant's family name, date of birth and country of birth.
In your case you should use the file number and your husband's family name, date of birth and country of birth, and as stated previously you should also send a case specific enquiry explaining that the applicant now resides in Canada, give the address, etc.
