On the Samsung Galaxy S6, you can assign for each contact a profile picture within the Android Contacts app. By assigning a profile picture you can see and find this contact within the contact list more quickly.
If you do not know how to assign on the Samsung Galaxy S6 a profile picture to a contact, then we would like to explain this in more detail.
First, open from the home screen of your Samsung Galaxy S6 the contacts app. You will now see all your contacts. Tap on the contact you want to assign a profile picture.
Then tap the top right on "Edit". You can now change the contact information, including the contact picture. Click at the "blank profile picture with the camera icon" to assign the personal profile picture to the contact now. You can either directly take a photo or select an image from the gallery. If you have made your selection, the profile picture is taken in this contact. Finished!
So now you know how to add a profile picture for a contact on the Samsung Galaxy S6.