How to install cordon wire for grape trellis?

I am setting up my VSP grape trellis. I drove two t-posts 8 feet apart. I bought 12 gauge wire. I also bought a turnbuckle, for tensioning.

How do I install the catch wire? Do I just wrap it around one post, then wrap it around the turnbuckle hole at the other post? So how would I connect the turnbuckle to the post?