2016 Update
Use the Sharing Debugger to figure out what your problems are.
Make sure you’re following the Facebook Sharing Best Practices.
Make sure you’re using the Open Graph Markup correctly.
Original Answer
I agree with what has already been said here, but per documentation on the Facebook developer site, you might want to use the following meta tags.
<meta property="og:title" content="title" />
<meta property="og:description" content="description" />
<meta property="og:image" content="thumbnail_image" />
If you are not able to accomplish your goal with meta tags and you need a URL embedded version, see @Lelis718’s answer below.