It is a 2 step process. 

In the interview section, you say you purchased a qualifying home 

Then click on the "Deduction" tab and payments profile. Enter $5000 here

Sorry, I do not see anything under the interview (setup?) section regarding the purchase of a home. I can only get information when I search for it and it will bring me to a screen that has no fields to complete other than a continue button which will bring me to a political contributions screen.