Well, to have photos save to the SD card automatically you would have to change the settings in your camera app to save them there. To move photos, music, videos, etc., (not apps) to the SD card, the fastest way to move them all is to connect the phone to a computer via USB cord. Move all the files over to an empty folder on the computer and then, while still connected via USB cord, copy them all back over to the SD card.
If you are wanting to move apps, that is a whole different thing. You would first need to have a phone running at least Android "Marshmallow" and second the phone would have to not had that option restricted by the manufacturer. Which happens quite a lot.
How to turn the "External" SD card into "Internal" storage...