Lubricate A then insert into B or alternatively C. Keep D and E handy in case you become exhausted by the mechanics of the thing. Repeat, perhaps, if you can be bothered. Refer to diagramme or instructional video if the thing runs out of steam.
Simple. That is all there is to it.
There are other things of course that I have spoken about when I was talking about sex, but here, I have removed them for the purposes of this demonstration.