Help with creating the simplest plugin in the world

I would like to exclude some core parts of WordPress without touching my theme, and thought that a plugin would be the way to acomplish that.

Now, I do understand the basic structure of a filter/action hook, but i cannot get the function right. Could someone please help me out with this?

For example, I would like to remove the post-title, or the meta-information, how do I go about in doing that?

A big thank you from Sweden,
Erika