duplicates of parts of a line in list

[hh]

Never mind, just try:
put myCounter(fld "X") into fld "Y"

That's life - more exactly, that's LiveCode:
s is an empty string, created by LC for you
f is an empty array variable, created by LC for you

Did you already look in the LC-forum? There is a lot of help and there are some impressively good helpers for such questions. I started there too at my very LC beginning, close to yesterday (time flows...). 

See you there, I'm only here today because its saturday (Craig?).

And there are very good tutorials to using arrays.
Both reachable from the top site of LiveCode.