Parallax background 2 layers

Hi, I have searched for a solution but do not know how you guys built the effect. So one the demo on the parallax background it has the gunfire going on and then the soldier appears in a front layer sliding in. How do you set that up to get that effect? I am still searching for answers online but if you get this before I find a answer your help would be appreciated. If I find a solution I will post it.

Thanks,

Kenny