The path I know of ----1. buy/download TurboTax 2017; 2. Prepare 2017 return making sure that it matches exactly what was produced by HR Block; 3. Now tell TurboTax that you want to amend; 4. Follow instruction and make the changes; 5. Print out the 1040-X and the 1040, sign/date and mail to the IRS and/or the State.
Note that 2018 software cannot be used to amend a 2017 return.