HOW DO I CHANGE BACKGROUND WITHOUT USING SOMEONE'S LAYOUT

hopefully this is what ur looking for lol

<style>

    body{

    background-image: url(PUT IMAGE ADDRESS BETWEEN THESE BRACKETS) !important;

    background-attachment: FIXED !important;

    background-repeat: NO-REPEAT !important;

    background-position: center !important;

    background-size: COVER;}

</style>