jax jungle is pretty easy and very good in carrying games.

with jax start frog and dont gank a lot because u have to stack Devourer.
try to gank bot and mid as they are the weak lanes and take all the dragons obviusly.
to engage a cam do Q W E and thats it.
a good advice is to smite wolfs always for the vision bonus and krugs for the stun and push power.

in teamfights activate your R and engage with E Q and your team should be able to kill them.
As jax try to focus the weak parts of their team like adc,mid.
With this build you will stay alive and take an easy double or triple

the lane you push is mid and you can do it vary good,you will push even in nexus turrets when you have your team without dieng