Can I download photos from my computer to my ipad

You can. If you have iTunes 11 on your computer then you may want to enable the left-hand sidebar via View > Show Sidebar (option-command-S on a Mac, control-S on a PC), which might make it easier to navigate.

To sync photos, connect and select your iPad on the left-hand sidebar 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 tab you can then select which photo folders to sync to the iPad's Photos app. 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 - synced photos can't be deleted directly in the iPad's Photos app, instead they are deleted by not including them in the next photo sync.