I went to the site for this product, and from what I can see from the pictures posted there,
1. You keep the base of the seat strapped into the kitchen chair,
2. You remove the cloth/padded liner that you would use for a baby,
3. You adjust the angle of the inner seat so the toddler will be sitting in an upright position, and
4. You remove the tray and push the chair up to the table.
This should make the high chair the right height so the toddler can eat from a dish placed on the table.
I hope this helped you!