When you are logged into your profile, in the upper right corner where it says "Your Houzz", click on that, and then in the drop down menu, at the bottom left of the drop down box, you will see "Edit Profile"
When in that, scroll down to "Cover Photos", where you have the opportunity to add 5 photos that rotate with your Profile when people scroll over your information. You can change the order of the photos, and change the photos once in awhile. I find the photos I post in Cover Photos tend to get added to more Ideabooks, so I change them every once in awhile.
Hope this helped!

Yes thank you very much! I did not know that the pictures rotated.