[AC Question]

Have a picture that was messaged to me, but want to save in Gallery or Photos for future use

[SpookDroid]

What device are you using?

In general, though, when you tap on the image from the message, it should be displayed in a 'mini' version of your Gallery viewer and there should be a SAVE button on the top. Depending on your device, this button will either give you the option to select the save destination or it will just straight up copy it into your phone's internal memory.

[srkmagnus]

Have a picture that was messaged to me, but want to save in Gallery or Photos for future use

You should be able to long press the picture and select save/download when the dialogue box appears. Otherwise, opening the photo then going to the menu > save should also save the image to the sd card. Let us know how it goes or if you have further questions.