Open the picture on your computer or laptop, and maximize it as much as possible. Then get your EVO and open the Camera application. Use zoom to match the viewport to the photo edges as best as possible. Try to hold your EVO very steady to avoid blur. Shoot the picture, and tada! its on your EVO.
Ok, seriously, there are about a dozen ways to put pictures on your phone:
- email to yourself
- copy to your mounted sd card
- bluetooth file transfer
- MMS to yourself
- wifi network transfer
- ftp file transfer
- dropbox app
- download from Picasa
- download from flickr
- download from Facebook
These are just the one's that I've personally used. Once its on your phone, view it in the Pictures app, and then select the option to set as wallpaper.