It would be in your MYCIC account where you got the form request. Proceed same way On how you submitted u r forms earlier before getting the AOR, then go view submitted forms, then click continue and then you can have special folder available to upload with the new form they requested. They requested my CElPIp score card and i see the same in there and uploaded and submitted and after few hours of submission i got an updated message to MYCIC account saying additional documents: Provided
The issue is that you might not have declared your BG properly (like education, history etc) while submitting your eAPR so they want to clarify that with your new doc submission. So dont panic as its always a good news if they ask something that we already know. This will intiate the BG soon once you submit this.