Here are simple instructions on pre-fitting the animal.  Although it is easier for two people to pre-fit, Dave is showing you how it's done alone. 

If possible halter your animal to a hitch.  Introduce the sling so animal can become acquainted.  Dave has sling, tie disk, neck & breast straps ready on his shoulders

 STEP ONE:

For suiting taller animals, have sling girth over your shoulder & slide in an upside-down position over animal's back & position it evenly.  Your sling is marked "This Side Out"  - If you see this, then you are doing good so far.