There are several boot logos available in Cydia. Have a look there; use the search term "boot logo". Or, if you go to the Sections tab, scroll down until you find the tab "Addons (BootLogo)." Again, there's a lot there - all you need to do is ensure they'll work on your iPad.
I don't change the logo, so I can't tell you which ones are good (or work). Hopefully, someone who has changed their's will chime in...
Marilyn
P.S. And, since you talk about a jail broken iPad, I've taken the liberty of moving your post over to the Hacking section. Thanks for your understanding.