Blending Two or more tracks up and down

I have a voice over track and I want a background sound track to go up and down in volume in the appropriate spots. How can I do this smoothly like I had used a slider control?


You can use the Envelope tool to vary the volume of your backing track. The envelope tool is accessed by the tool button with the icon that looks like a white dot with two triangles pointing at it and a blue-line going through it.

When you activate the envelope tool you will see blue lines added to your track - you can drag these around to change the volume.