Dance Central 2

To upload a photo, after playing a song select the 'Photos' option, select the photo you wish to upload and confirm. It will automatically go and the achievement will pop immediately. Kinectshare is private, so don't worry about your flattering photos hitting facebook. Although you can do that from kinectshare.com if you really want! They can also be deleted if you're THAT uncomfortable with your pictures being up there!

This achievement has been discontinued. Harmonix closed the servers to deal with XB1 stuff. You can try emailing Harmonix to try and get the Facebook support back up, but they probably won't.

Also lots of Facebook XB360 achievements are being discontinued, so if you have any get them quick.

Update, July 6, 2020: I even tried experimenting a lot with the sharing feature. I suspect this achievement may have been possible between 2015 (when Facebook changed their APIs and Facebook achievements across many Xbox 360 games became discontinued) and 2018 (when Microsoft officially dropped all Facebook sharing functionality from Xbox 360) by tricking the game into thinking you've uploaded a photo, but considering all Facebook sharing functionality is now discontinued on the Xbox 360, I don't think it's possible anymore to even trick the game into thinking you've uploaded a photo.

If you'd like to watch what I did to experiment, I've left a video below. I don't know why in the world you'd ever want to watch it, but it's there if you want to. I am officially declaring this achievement PERMANENTLY DISCONTINUED

As previous solution is obsolete, this is how it happens for the day I write this.

After finishing a song, when you go to the photos menu, you can choose a photo to share (within 17 with freestyle enabled or just 1 "final pose" with freestyle disabled or in "Crew Challenge" mode no matter what the setting is). When you do that, Xbox asks you to log into Facebook. It uses the "Dance Central 2" app (https://apps.facebook.com/dance_central_two/) which will ask you to post on your behalf. If you don't allow it, achievement won't pop, so if you don't want anyone to see the photo, proceed as follows. Using for example PC, change your future posts visibility to "Only me" (here's a screen where to do that: http://bit.ly/1fPLmVK). App also creates a separate album "Dance Central 2 Photos" where it puts all the stuff, but don't worry, the visibility of the photos as well as the app itself (https://www.facebook.com/settings?tab=applications) also matches previously set future posts visibility. Achievement will pop when DC2 says that upload is complete.