Help Shadows and real world reflections

ok how would i add real world refecltions and shadows in my 3d composte videos by shadows lets say i out a 3d car in my videos in blender and it goes under a tree and the tree has lots of shadows how would i make the trees shadows effect the fake 3d car after motion tracking of course :eyebrowlift::mad::o

For the tree shadows it’s as easy as adding a plane, apply a leaf texture to it and make sure it affects the alpha channel like this.
Then you enable shadow only (material->shadow->shadow only).
The car material should have recieve transparant enabled so it can actually recieve the shadows.