How to get my camera to focus so I can take a photo like this? (LINK)?

I'm in LOVE with this photo and I would like to try and imitate it. I have the Nikon D5000 which I recived two days ago and I'm still new at using it. I know the basics but I would like to know how to focus my camera on an ornament like that. I tried a couple of minutes ago but it came out blurry. And I kind of know how to make the background bokeh-ish and blurry like that. You just lower the aperature number. But I'm really wondering how I can manually focus on my reflection on the ornament.

You already answered your own question, open the aperture all the way, switch to manual focus and do your best. The pic you posted was shot with a d60 with an 18-55 so you could do this with a d5000 and kit lens as well.

There will be a minimum distance which your lens can focus at - you need to either get close with a lens capable of close focusing, or stay further back but zoom in. You'll need to open up the aperture & if the shutter speed is too low you'll get camera shake, so increase the ISO to give you a decent shutter speed.

Here's one I did using a wide angle lens;