How to replace the passenger side headlight assembly on a 2007 Toyota Sienna

I ordered an aftermarket headlight assembly and now need to replace the original which was broken when I hit a deer.  The body panels are intact and not dented, only slightly misaligned.  The outer shell of the headlight assembly is not broken, however, many internal components are including the buld deflector shild as well as some of the moulded external mounting ears of the headlight assembly.  I have never removed body panels before and need to know how to get started.