adding meta-box to post/page editing page

I wanted to add a metabox at the post/page edit page. These metabox would contain some instructions on how to post things, and nothing more. Can anyone tell me how to do that?

I googled around before, but the only examples I found was adding the metabox into the dashboard, while I want to put it inside post/page edit page.

I’m rather clueless here, so a simple example would be very much appreciated.

Thank you.