Next you need to cut the steel cable to length. I cut mine to about 6 feet long since I cant reach anything much taller than that. If your going to running it horizontally on the wall then it can be any length you like.
Its easiest to use a cable cutter to do this (shown in first picture) - its about a 10 dollar tool at the hardware store. If you don't want to pick one up you can use a wire cutter or any others pliers with a cutting surface and just try to slowly work your way through the steel cable in a circular twisting motion between your hands (shown in second picture). This takes some time and requires a good deal of effort so be warned.
Hack saws can make pretty quick work of steel cable as well if you can get someone to hold the cable while you saw it.