Get your taxes done using TurboTax

It’s two separate transactions.  You rolled over the 401(k) into a private (pre-tax or traditional) IRA, and then in a separate step, you rolled the traditional IRA over into a Roth IRA, which is also called a conversion.  I assume you paid income tax on the conversion amount?  The amount you paid tax on is the basis amount added to the Roth.