Hi Madgreek,
firstly you should add some logic. Use an event case to wait on the start button, so you can browse for the path inside the program.
Secondly read the sound format from the wave file and use that to decide which stream to use and which sample frequency.
Now about the Rxx x-axis, you should now that the autocorrelation always (
always) tops at zero (the help showed that)
In my attachment I have programmed that.
The only thing you have to do (and do that since it will raise your grade), is make the program wait on a start button (no not the run button) OR lauches a browser window that will browse for *.wav files only.
Ton