you mean the badge color? well... if it is that then just go into cydia and search for badge and it will give you alot of options on color.. and if you have your own and your on ios 4.+ ( am not sure if this will work on lower ios) then just name it " SBBadgeBG " . if your doing it for winterboard then it needs to go into a folder called " SpringBoard.app " and that will have to go into a folder called " Folders" and folders has to go into whatever you want the folder to be named. if thats too hard to understand then here. : yourfolder -> Folders -> SpringBoard.app -> SBBadgeBG.png
please remember that THAT is for ios 4.+ only .. not sure if that will work on others