[Koha] about patronimages and photo of borrowers

Hi, I've a question: When i enabled the system preferences "patronimages", photo of borrower can be imported in koha but 1)where these photos are located in koha? 2)where i have to define the source where i dowload photos? 3)How is made the link between the borrower and his photo (all the borrowers com from our ldap)? Thank you. Best regards, Samuel