If the source files has a varying tempo then you'll need to tempo map it, if it's a constant tempo then you can use the Alt key and drag the end of the file to align with the beats.
Thanks for informing me about the Tempo Map; never heard of it before.
So I displayed it and it does show it at the top of the screen but it doesn't seem to be analyzing my audio waveform to determine the tempo(s). It displays one tempo value, which after some exploration, is the same value set at the bottom of the screen.
Is there a way for it to determine what the tempo(s) are throughout the song?
If yes, can I then specify a constant tempo which it would then alter my audio to play at?