Sometimes when you attach a link to a Facebook status, Facebook doesn't automatically pull the description or image you want.

Note: The preview image will autodetect from the page body and the Title and Description will feed from the Meta Title and Meta Description unless you specify otherwise in your code using open graph code.

Once you have fixed what was causing the preview to pull in incorrectly on your website, you will need to clear Facebook's cache so it knows to pull in the new data.

To do that, go to Faebook's Developers Debug Tool: http://developers.facebook.com/tools/debug

Copy and paste the URL you are refreshing into the box and click "Debug." The tool will show you diagnostics on the URL that you can ignore.

Now refresh your Facebook window and repost the URL. Facebook should now pull in the updated data.