How to customize startup screen

I found this on YouTube https://www.youtube.com/watch?v=h3hRgYwraXs and I thought I'd share just in case you didn't know. I thought it's a neat idea. I put my name and phone number so if i ever lose my device on a mountain bike trail and someone else finds and is kind enough to return it to me it, it has my info. Apparently it's an oldie-but-goodie tip.