There is a Trainer's heading on Breeder Connect, but there is only one listed. If you are looking for a trainer, you can put a want ad on the Wanted forum and people can contact you vis private message, or you can also post a want ad on the Saleboard.
Also be sure to post the type of training needed....some specialize in halter, some in driving. I see you are in Texas....quite a few trainers in Texas, Oklahoma, Arkansas.
Even if you aren't a member of AMHR or AMHA, the magazine links for them are above. I found the trainers I utilized thru those magazines (no trainers listed in trainer classifieds, but looked thru the various ads of barns and trainers) and thru the clubs in various states.
I also went with a recommendation from a breeder I purchased a pony from.