We don't get many of these 1907 slings on the line, but when we do, it's not unusual for us to see some confusion on how to use it correctly, even on the part of, ahem, instructors. &)
Here's a new video on the subject that I found helpful:
http://www.2ndamendmenttv.com/videos/basics/using-a-leather-rifle-sling--to-improving-your-shooting.html
Be Safe,
Firewall99
If you look up Blackfork6 on youtube you will find a number of good shooting related videos.
Mike