Retirement tax questions

I think I'm trying to do the pretty much same thing as what Jman42 describes: entering the conversion of a portion of an existing trad IRA to a Roth and showing that I paid the 4th quarter 2023 estimated tax on the full amount of the conversion by the Jan. 15 (or whatever it is) deadline.  Surely this is a very common thing for retired folks using TT (I'm using 2023 Premier Desktop), yet the only instructions I can find are the same ones that Jman42 found for a "Backdoor Roth IRA conversion".  I think I understand how they might work for someone who still has earned income and can make a contribution to a trad IRA, then convert it to a Roth, but it sure doesn't fit my situation.  Very frustrating!  I'm hoping someone out there can point me in the right direction.