Need a explanation of VFX Workflow

i have been using blender for a while and i stumbled across people using it for live action footage, i can model, slightly texture and understand ,how camera tracking works, but i want to understand how to put cg elements in live action and match then up

so can someone give the workflow of:

  1. live actor in a cg world
    2)cg object in live footage

Hi, this could help:

There are hundreds of youtube tutorials. Pick any.