To start teaching jump command, you may use a pipe or a stick.
hold the stick pointing the wall/fence with very low height, put your dog one end and hold a treat on the other end command him 'jump', they will instead trying to get the toy/treat, will just jump over to reach the treat.
Please be patient and start this with only very low height and eventually increase the height slowly.
After he can master the jump you can put the stick balance on some obstacle instead previously using the wall/fence. If your dog can not jump even with very low height, put the stick on the ground just guide him walk over and give command 'jump', you can replace the stick with a blank wood, some dogs fears when they see there is hollow under the stick, a solid blank wood can give them better concentration or prevent they go under the stick to skip the jump command.
After he understand the jump command, try the jump on different obstacle, like hoola hook, furnitures.. etc.
make sure you have very good landing area to avoid injury to your furkids. You can try this on grass or sand floor if you don't hv rubber mat.