Samsung Galaxy S6 User Manual page 191

 The Gallery app opens.
2. Tap the pictures or videos you want to share.

To select multiple items, touch and hold an image to turn on multiple select. Tap all the items
you want to include.
3. Tap SHARE, and then on the sharing menu, tap Messages.
 Follow the onscreen prompts to complete and send the message.
For more information about sending multimedia messages, see
Camera and Video
Send a Multimedia Message (MMS).
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