Next put the leather into the coil.  Take a pliers.  Insert the coil all the way into the pliers (we don't use the tip of the pliers).  

Crush down the first 1 or few coils onto the leather.  Make sure you don't go too far down so that your cut the leather.  

Hold the coil with one hand, and pull on the leather with the other.  The coil should expand a little bit, thus signalling that the clasp is secure.  If the leather starts to pull out on its own, than you need to crush the coils down a little bit harder.

At the end of the coil is a ring.  Ideally, you want to attach a clasp to one side, and either use the ring on the other side as is, or attach a jump or split ring to it.  The Lanyard Clasp is great because you can slide it right onto the coil-ring.  With other clasps, you will probably need a jump or split ring to connect the coil-ring to the clasp.  The concern here is that the coil-ring is somewhat brittle.  If you move the end of the ring too far, in order to open the ring up so you can slide a clasp onto the wire, sometimes this coil-ring will break.  Be careful.

NOTE:  For 2mm cord, it's better to use the 1-2mm coil end, rather than the 3-4mm coil end.   If the cord is too large for the opening, shave part of it down with a razor blade.