At the trailhead you should find a set of pamphlets with interpretive information about the track. Pick one up to bring with you because all you'll see along the trail are number markers - for you to refer back to the pamphlet you should have picked up at the trailhead.
After a short climb up a few switch backs and over Yoho Valley Road, the trail dumps you out right on the active railway running through the park. If you time things right, you'll get a front row seat to this picturesque mountain and train view.
Carefully crossing the tracks and walking along an old road, you can follow the signs towards the carcass of an abandoned narrow gauge locomotive used to build the Spiral Tunnels.