Just click it to toggle it on or off. Auto-Progress will make you progress to the next level when you finish one. If you're talking about Auto-Upgrade, just turn it on and it'll buy gold upgrades for you every 30s. It doesn't unlock until you have some points in the Profit upgrade though.
 "Idle Mons"){kind=icon}
 "Idle Fight"){kind=icon}
 "Final Ninja"){kind=icon}
Just click it to toggle it on or off. Auto-Progress will make you progress to the next level when you finish one. If you're talking about Auto-Upgrade, just turn it on and it'll buy gold upgrades for you every 30s. It doesn't unlock until you have some points in the Profit upgrade though.