1. Open the Gallery app.
2. Navigate to the photo you would like to share.
3. Tap and hold your finger on the picture you want to send.
4. A menu will appear where you can tap Share.
You don't need to go to the gallery to forward a text message.
In order to forward a pic from a text message as a text message, press and hold the pic in the message, a menu pops up and you can forward from there.