Here we are teaching the filly to Stand on The Mat, Take Your Mark, or Ground Tie.
The "mat" or "mark" can be anything you choose: a doormat, a piece of cardboard, plywood, towel, etc. The horse should have the opportunity to smell, lick, bite, touch, and / or bang on the mat. If you use two or several different "mats", give the horse the opportunity to investigate each one before asking him to stand on it.
Start with click and treat for interest in the mat, and then for targeting the mat.
Up the criteria to touching the mat with a foot, and then to rewarding standing on the mat with one foot.
At this point, the question might be: How do I get that one foot on the mat?
If your horse is used to following your body, you can use your "chi" to "pull" him into the right place, or he can follow your body language, or you can support him and / or guide him with the lead rope.
The next criteria would be to click for both feet on the mat.
Once that behavior is established, you can extend your "thread". Click and treat for a positive response to: "Can I move one foot away from you while you stay on the mat?"
When ready, up the criteria to being able to walk around the horse while the horse stays in the same spot. Increase your distance away from the horse. Click and treat often.
Jord-Ann, from the ClickRyder group, adds:
A few ideas that helped me get some side benefits from this exercise: Once the horse has his feet on the mat, I ask them to target the mat and keep their nose on it as well as their feet. This not only ties the exercise to something they already know, and helps the idea of a ground tie by keeping the feet still, it also gives me that last little bit of head down (nose in the dirt) that can be elusive. You can then fade the mat and ask the horse to target the ground - another way of looking at a ground tie/head down.