If your friend sends you a photo in an MMS text message and you wish to save it to your Samsung Galaxy S4, you can get it done with these steps.
1. Open the message thread that contains the photo from the Messaging app.
2. Tap and hold the image until a menu appears.
3. Select Save attachment.
4. Check the box next to the attachment(s) you wish to save, then tap Save.
The photo is now saved to a folder called Download and is viewable from the Gallery app.