Grabbing an external web page

I'm looking to grab pieces of information from a page on another site that is standard HTML. I know how to read and write the page to my site and event extract the information if the page is XML. Where I'm stuck is how to get to the portion of the page to read specific data (i.e. the weather forecast for that airport). I'm just looking for some direction, or even some example code that does something similar so I can learn from it. Thanks! Mark