A ratchet strap is an efficient way to secure your cargo, but since your strap most likely came without instructions, here's a quick and easy instruction guide. These instructions should work for any ratchet strap. Regardless of the size of your strap (they usually come in 1", 2", 3", or 4" widths), they all work the same way.
A ratchet strap usually comes in two pieces, so the first step is to attach the sections. To do that, just feed the strap through the slot in the attached handle and ratchet (move the handle up and down) until the slot is pointing straight up. That will allow you to feed the strap through easily.
Next, pull the strap tight and hook it up to whatever you're loading. Be sure to keep the strap straight as you're working with it. If it gets twisted, it could bind up.
Hook it up on each side, making sure you don't leave too much slack. This is a common mistake. If there's excess slack, the strapping material can get bound up in the handle when you start ratcheting, making it hard to release. If the binding is severe enough, you could even end up having to cut the strap.
After you get two points hooked up, all you have to do is pull the strap tight. Line it up, again making sure you keep everything in line. Once you've done that, grab the handle, pull the release, and ratchet it until it's tight. Be sure to flip tite move the handle back down to its closed position when you're done ratcheting.