Check the back packaging of the DVD. Make sure the DVD states it is printed in the United States and is region 1. Oftentimes DVDs are produced in Europe or Japan (region 2), which do not play in your DVD player.
Open the drive to the DVD player, then insert the "Made in U.S.A." DVD. Close the DVD drive and wait for the DVD's main menu to load onto the screen.
Press "Play" on the DVD player and the video begins to play on your Canadian DVD player.