The iPhoto Library is usually kept in the Pictures folder of a user account. One way to do this would be to put both computers on the same local area network, turn on File Sharing (found in System Preferences > Sharing) on the old MacBook, connect to the share with the MBP, and copy that library over to the new computer. Next, launch iPhoto on the MBP while holding down the option key on your keyboard. When prompted to select the iPhoto library you want to use, select the one you just dragged over.
Best of luck.