Before you start putting the fence posts into the ground, tie the last fence post to the first one and to the your support post. This helps immensely as you do the next step.
Now, you can go around the fence, starting at one end, and set each fence post into the ground, making the fence upright. When you do this, make sure to pull the bottom of the net fencing taut, and pull each post to the very end of the section of netting it's on, so that there is no slack in your fence.
You will find that there is some floppiness of the fence, especially at the corners, but you will fix that in the next step.