Did you purchase the download version of TurboTax? If so, when you purchased, you should have received an email from us with instructions on how to download and install your software. You need to track down this email because it also includes the Installation Key Code you need to complete the installation.
If you prepurchased an online return, just sign in to TurboTax (upper right corner at TurboTax.ca) and start a return. When you're done and it's time to pay, you'll enter the pre-payment code that was emailed to you back when you prepurchased: https://turbotax.community.intuit.ca/replies/2648021
