Chrome extension, how to Modify page content (add something) [duplicate]

Question

I'm new to Chrome extension development, my first project (to learn) is to create an extension that adds some html to another website's existing page.

I plan on creating a 'page' action which fires for a page with a certain URL...

Has anyone seen a tutorial like this, or do you know of an API for adding html to a page?

Answer 1

You can find some example at Google Sample Extension page, however your question seems better answered on this other question.

Answer 2

There are a number of sample extensions on the Chrome extension API site. There are a couple of browserAction examples that will be almost identical to using pageAction.