To send a picture, do the following:
1. Go to your camera roll and select the photo or photos you want to email.
2. Tap on the upward pointing arrow in the bottom left corner.
3. Tao on the mail icon
To reply to an email message by adding a picture,
1. Open the email app and locate the specific message.
2. Tap the curved arrow at the bottom.
3. Select "reply"
4. Tap or double tap on a blank space in the body of the message until the menu appear and then select the arrow at the right of the menu.
5. Select "Insert Photo or video"
The rest should be common sense.