If there is an amount in Box 12 of your W2 reporting contributions made through work to a retirement plan, the software is getting the information from that.
If that is not your situation, and you need to get back to that section,
Sign into your account and your return
Click "Pick up where I left off"
Click Federal on the left side bar
Click Deductions & Credits along the top
Scroll down to Retirement and Investments
Continue through that section.