how do i download my photo on ipad,

Connect the iPad and select it on the left-hand side of your computer's iTunes, and on the right-hand side there should be a series of tabs, one of which should be Photos - if you select that you can select which photo folders 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 - not including photos in a subsequent sync is how you delete them from the iPad.