Q: can't download images from a computer on the iPad than in?

I'm not entirely sure what your question means.

If you want to sync photos to your iPad then connect your iPad to your computer and select it on yoru computer's iTunes, and you should have a Photos tab :

You can use that tab to select which photos to sync to your iPad

Syncing photos : http://support.apple.com/kb/HT4236

You 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 on the iPad, instead they are deleted by not including them in the next photo sync.

If you mean something else ... ?

iOS and iPod: Syncing photos using iTunes

http://support.apple.com/kb/HT4236

Another way. You can use a USB flash drive & the camera connection kit.

Plug the USB flash drive (works the same with an SD card) into your computer & create a new folder titled DCIM. Then put your movie/photo files into the folder. The files must have a filename with exactly 8 characters long (no spaces) plus the file extension (i.e., my-movie.mov; DSCN0164.jpg).

Now plug the flash drive into the iPad using the camera connection kit. Open the Photos app, the movie/photo files should appear & you can import. (You can not export using the camera connection kit.)

Using The iPad Camera Connection Kit

http://support.apple.com/kb/HT4101

 Cheers, Tom