You will need to fill out Form GST191, as well as the worksheet Form GST191-WS. These are not available in TurboTax. However, you can download them from the Canada Revenue Agency (CRA) website:
GST191 GST/HST New Housing Rebate Application for Owner-Built Houses
GST191-WS Construction Summary Worksheet
You may also want to look at this page which has more information on this rebate: RC4028 GST/HST New Housing Rebate