I went through the overview, etc. for Chrome extensions programming, and looked through some of the samples, however, being very unfamiliar with this world, I cannot figure out how to do what I want in an extension.

If I could see a very simple implementation of the mentioned "Find unlinked URLs in web pages and convert them into hyperlinks" extension (mentioned as an example of what you can do with content scripts), I'm sure I could adapt it to do what I need.

I just need to insert some HTML (can use Javascript, of course) into web pages when a certain condition is met. I would also like to add a random aspect, but I'm sure I could figure that out in the Javascript code. I'm just not sure how to insert code based on a condition (a hyperlink tag, for instance).

Any help would be greatly appreciated. Thanks!