In the sling package there should be four items. 

1. Sling (Frontend of the sling has the cam lock buckle)

2. Front handguard sling adaptor

3. Attachment extender

4. Buttstock adaptor

Attaching Sling

Not all pieces are needed depending on the type of buttstock and handguard you have on your rifle.

Attaching sling to the buttstock:

If you are using a traditional M4/AR15 collapsable buttstock you can eliminate the use of the buttstock adaptor (#4). Most M4 buttstocks have a slit opening towards the middle rear of the buttstock (See image below). This is where the first anchor point of the 3 point sling can be looped through. Loop the rear of the sling through the slit and around the stock, then secure it by slipping the nylon through the triglide.  This will keep it locked into place.