Best for merging?

[Shadow400x]

Hello, guys I have been working on a documentary style series that have .3gp's on my channel Shadow400x, I have been wondering how do i put like ghost effects or a slenderman standing in the hallway? Thanks

Shadow

IT ALL STARTS HERE:

 

[John The Dad]

The best way is to first film your hallway. Then film the person ether against a green screen or against a black background, making sure you don't get any light on the black background, then chroma key the person on your hallway reducing the opacity of the footage.