Depends on the phone. With an iPhone you can use iTunes and add the picture as a photo then sync to the phone and use the picture from the camera roll as a background. What I did was put it on my dropbox account, opened it on my phone, saved the photo to the camera roll then set the lockscreen.
http://www.reddit.com/r/nfl/comments/1f215d/gentleman_ive_made_a_season_schedule_designed_to/
There are screens for every team, in case you have some friends with other tastes.
Direct link to reddit thread - ( New Window )