Before you can train a barrel horse -- or a jumping horse -- or a cowhorse -- or a ????? Horse you have to learn basic horsemanship first.
To take on training a barrel racing horse and not get a neurotic crazy unridable idiot, you have to learn how to ride and you you have to ride very well.
What you are attempting is like saying I am going to buy a race car and start racing it -- when you don't even know how to drive. It is just not going to happen without the proper foundation being carefully laid. Your chances of succeeding without ruining the horse and your confidence are nil. Find a trainer that will let you work for them for nothing or get a year's lessons at the rate of 2 or 3 a week. You just have to learn to walk before you run -- literally.