Check out this question: How to set up speed dial on the Samsung C3590?
I think the post in that page will help. :)
Hello Diana, the Settings for Speed Dial are normally located in the Phonebook or Contacts menu. So go to that part of the phone and check out your options for setting up speed dial. Also, check to see if speed dial is already active by calling numbers 1-9 on your phone. You may just have to reassign the speed dial numbers if the feature is already enabled. Hope this helps!