Once you determine what the signal needs to be, put a boolean value (T/F) to it and wire that result to the While loop "run/stop" input.
For Example, if your signal to stop the loop is a specific value (eg counter = 100), use an "Equal?" vi to 100 and wire into a Select vi (from the comparison palette). When the counter = 100, have a constant "True" go out, else a constant "False" (which is wired to the while loop "run/stop" input).
Good luck with it, Doug