To add profile images to participants,
First create a Profile image field by going to:
Field manager,
Select +Field
Provide a Display Name and select Field type 'Image' and Field Category "Personal information"
Select Proceed:
Then fill in the desired configuration options,
Select Proceed
Then go to Participants
Select the desired participant and under personal information there should now be an option 'Profile Image'
Select the paper clip.
Browse for the desired image
Select Save