[Cableguy69]

Either use the Stylevar to change the Titleimage, image path, or simply right click on the Vbulletin logo and find the image location of it. by default it's

root/images/misc/vbulletin4_logo.png

You can then make your new logo and name it vbulletin4_logo.png and upload it to root/images/misc

I would advise you look at the Stylevars though as they are really easy to use and give you more flexibility, ie: you won't have to use a .png file you can use whatever you like, .jpg, .gif, ect, ect although I can't think why anybody would want to use .gif or .jpg over .png tbh.