HELP HOW DO I CHANGE MY BACKGROUND

IDK HOW TO CHANGE MY BACKGROUND PLSS KAFHKJE

thanks 4 the add ^_^ stan (G)-idle

thanks for putting me in your top 8! ^^

THX FOR THE ADD, if u need help with css i have my css links on my profile!!~
https://media.tenor.com/images/07245006bfce43be31817d244649b8db/tenor.gif

Thanks 4 the add!