AC meter By ADC timer interrupt from Nick Gammon
You can read two analog channels like this:

int first_reading = analogRead(A0);
int second_reading = analogRead(A1);


If this does not fit your purpose, then your question was not asked
properly: rewrite it and clearly state your requirements. Explain why
the simple solution does not work for you.

If this does work for you, then stop (for now) reading advanced
tutorials, like the one where you found your code, and focus on the very
basics: the Arduino examples in the 01.Basics section, then the
03.Analog section.