Green screen - need to match the lighting with the scene

Hey guys,
I am making a short movie and I came across this hard task. We have filmed our selves with a green screen and need it to look like we're on the edge of the building. Everything up until this is fine, but the lighting doesn't match at all. Maybe someone could please help me with this and try to match the lighting? I'll include the scene and us with alpha layer. Also could you please upload the project file for me? Because it's a scene, not just one screen :)

Here is the photos: http://www.2shared.com/file/CVLPR7S6/Photos.html

Thanks to everyone who helps me!

Hello!