Riding school?

I bought a horse that was enrolled in a riding school. How do i enter other horses in riding school?

when I went to the school I completed that horses training. It said I had no other eligible horses but is it because I have no others in show jumping?

Any horse can be placed into any riding school (no matter the discipline). Horses must be at least 3 years of age and they cannot have been entered into shows for the day. So basically, you can either show your horses or put them in the school. The school can be particularly useful for horses that don't show well. You can do a search for riding schools by going to Town and stable search.