You can start here: https://turbotax.intuit.com/personal-taxes/online/file-your-own-taxes/
The link posted above will take you to start an Online return. You bought the Desktop program. Did you get the 16 digit License code in the confirmation email?
Amazon how to download and install your software order
https://www.amazon.com/gp/help/customer/display.html?nodeId=G2CJPY7HHXBLMR5E
To get the License Code from Amazon, One user said......
I was just having this same issue, but I just figured it out. So I thought I'd share in case you are still looking for an answer. Go to Your Account; then Digital Games and Software (under Digital Content and Devices section at the bottom middle); your TurboTax purchase should show there under Downloads and Codes; the license code will be the 16 digit code next to "Activation Key". Hope this helps!
If you have the 16 digit License Code you can download the program from here,
How to get started with the Desktop program, install and activate it
https://ttlc.intuit.com/turbotax-support/en-us/help-article/product-delivery/download-software-turbotax-com/L7u9oLEkq_US_en_US?uid=luqgvzrd