Any picture you have saved inside your iPad, in the Photos library, can be emailed as attachment in a message. As you'll learn in this tutorial, you can even email multiple images at the same time. Since you can also access the files saved on your iPad from your computer (Mac or Windows PC), you can also email them while your iPad is connected, by going through Finder or Windows Explorer, but emailing images from your iPad is the quickest way, and doesn't require anything special. As long as the image files are inside your Photos library, you are ready to go.
Follow these steps to attach one or more images to an email on your iPad:
Tip: while you are seeing the images inside the body of the email on your iPad, not everyone will see them "inline"; rather, they will see it come as an email file attachment. (A notable exception -among others- is Apple's Mac Mail, which does show some attachments like images previewed inside the body of the email.) Make sure that, for all others, you are including a quick note that says that pictures are attached to the email.
If, while you are in multi selection mode, you notice that the "Email" button has become disabled (grayed out), it simply means that you have selected more than 5 pictures from your Photos library. Since your iPad will let you send a maximum of five images per email message, you may need to unselect one or more photos by tapping on them (it deselects). Then, send up to 5 images as email attachment, and continue with the next five, etc.