Here's a link to tying the knot. I don't have time to take pics and post tonight but can later if need be. To make a good throwing knot, pull the mainline of the rope to make the loop smaller until it's basically gone. It'll be right at the end of the knot. Experiment with the length of the knot. If you're trying to throw it high, at some point the knot will get too heavy and you'll loose height so just play with it.
When you're tying the knot and adjusting the loop, keeping pulling the mainline until the loop disappears into the knot. If you keep pulling the loop through the knot you'll see how the knot unravels untying itself. That's how it frees itself if you get it stuck in the tree.