Schedule 3 - section 4 - Real estate sale.

Thank you, I did look at that however I'm confused as to where to put the purchase price

When you click on that section in the Schedule 3, it takes you to the Capital Gains screen.  Under transaction type, it is real property, dates to record, Proceeds of disposition, and adjusted cost base (ACB) is your purchase.  Purchase includes other costs of the purchase, like legal, etc.