Posting to a Facebook Wall?

Using the PHP PHP SDK, what steps should I take to allow a user to post to their Facebook wall from another site?

For instance:

• User logs in to an external website
• The user creates a message.
• The user clicks "Push to Facebook" before submitting.
• A generalized post appears on the Facebook wall (Soandso has just been posted to mysite.com/entry/page!).