To make the image below your desktop wallpaper:
Right-click on the image below;
Left click on "Set as Desktop Background" (or "Set as Wallpaper")
Easy as that, and yes, you can change it easily. See all Jen's Christian wallpapers at "Desktop Wallpapers".

Philippians 4:7: "And the peace of God, which transcends all understanding, will guard your hearts and your minds in Christ Jesus."