Longeing is an art form and far more involved than mere circles. Like riding it requires that a certain set of basics be in place before moving onto the next level.
Clearly your horse has no concept of longeing or the aids, so you have to start from the beginning.
The 'old school' way of teaching longeing involved two people, the person with the longeline and whip and the 'helper' on the opposite side with a lead to reinforce the introduction of the aids. It doesn't have to be done that way, and one knowledgeable person can do it on their own, but that is the original way and makes things easier.
It would take me an hour of typing to tell you how to introduce your horse to longeing, but still w/o someone there to correct 'you', it would really be a futile attempt. So my best suggestion is that you employ a knowledgeable person to get both you and your horse started firsthand.
The horse should be in a longeing cavesson, longeline and whip are held a certain way, the aids are very specific (for instance the actually whip aid to push the horse out onto the circle is to point the whip at the girth...to push just the shoulder out it's pointed at the shoulder, to push the haunches out it's point behind the girth), etc...
You could also pick up a book on longeing.