Dance Central

This will come over time. Each time you play a song in either Perform It! or Dance Battle mode, you will have pictures taken of you whilst in Freestyle.
The number of shots taken per freestyle will depend on how well you do throughout the song.

While playing the song, you will notice some flashcards have a camera icon next to them. Pass this move to have that camera "added" to your freestyle -- That is to say, for every "camera move" you pass, you'll have one extra photo taken of you during Freestyle.

If you're planning to go for Dance Instructor then I wouldn't worry too much about this achievement, as it is likely you'll have it by the time you get there. Just play this brilliant game, enjoy it, and this'll pop up sooner than you think.

A very quick way of doing this is to enter Dance Battle mode either by your self or with a friend this way you can go for the 10 dance battle's achievement as well. Both you and your friends pictures contribute to this achievement.