help :(

HELP OKAY SO HOW THE FRICK DO I CHANGE THE LIKE UHHH HEADER THING WHERE THE HOME AND FRIENDS BUTTON IS.
LIKE I WANT TO MOVE IT TO THE MIDDLE AND CHANGE UP ITS APPERANCE OR LIKE CHANGE THE TEXT AND MAYBE MAKE IT A GIF!!
PLS IF YOU KNOW HOW PLEAAAASEEEE HELP MEEEEE AAAAA
EITHER SEND ME A MESSAGE OR LEAVE A BLOG COMMENT PLSSS
AND THANK YOUU
OKAY HAVE GREAT DAYS AND NIGHTS EVERYONE <3 :)