You cannot do this directly on the iPad. You need to establish the folders on your PC, place the photos in them, and then sync your PC and iPad. Then those folders will show up in the iPad's Photos app.
Also, a photo that has been synched with your PC cannot be deleted on the iPad - you have to delete it on the PC and then synch. However, photos that have been directly imported to the iPad - perhaps as email attachments - can be deleted on the iPad directly.