How can I transfer a file of older images from my macbook pro to my new iPad.

You can sync photos from your Mac's iTunes to the iPad's Photos app - once they are in Photos then the iPhoto app should see them as well. To sync photos, connect and select your iPad on the left-hand sidebar of your Mac's iTunes (you can enable the sidebar via option-command-S on a Mac), and on the right-hand side there should be a series of tabs, one of which should be Photos - if you select that tab you can then select which iPhoto albums to sync to the iPad. There is a bit more info on this page.

You will need to sync all the photos that you want on the iPad together in one go as only the most recent photo sync remains on the iPad -photos synced from a computer can't be deleted directly on the iPad, instead they are deleted by not including them in the next photo sync.