Not a dumb question at all. I had the same question a while back. You can either copy them directly from the site you found them by tapping and holding over the image and using the "save image" button. The picutre will then be saved in your photos on the iPad. Or email them to yourself and use the same technique. Those have been the easiest ways for me.
Or get a dropbox account if you have it on a mac/pc if you dont want to sync. Dropbox is free and there is no down side to having one. I highly recommend it. Great for things like this.