That's right, you don't put html code.
See, hubpages already has the html code put in with their id#, and when you put yours, it will allow them to switch the id# to yours instead. (more or less. It's a bit more touchy than that, but that's the drift)
So just locate my account -> affiliates, and do the steps to put in analytics and adsense and then hubpages will do the rest.