You may want to watch our how-to video here.
The three pictures for your profile page can be replaced via your Edit Profile page.
You can remove them by logging in and viewing your profile. Under each picture is a Delete link.
The picture that displays on the Home Page tabs is chosen at random. The picture that shows on the search page is normally the picture in position 1 on your profile.
If you are viewing your profile and you cannot see the new images, press CTRL R to refresh your view.