How do I install a generator pass through?
This is what you would use for a regular house receptacle in the us.

For the outside use a "inlet receptacle"



Then you need a cover for it while not in use.



Ideally a bubble cover or an in-use cover would be best.  If I find one I'll edit this.

After you get all this and you will need for the inside a cut-in box, receptacle and cover.  A piece of 12/2 romex or NM to go between, wiring the black wire to the brass screws, the white wire to the silver screws and green wire to green screw.