1. You can use the phones File Management app (or install one if you don't have one) and through that app move files from the phone to the card.
2. You can move them over via a USB cord (as mentioned above). You would connect the phone to a computer via USB cord and then use that as a means to move the files from the phone to the card. Personally I would suggest backing up a copy to the computer so you have it should the phone die, be stolen, etc.
You may also want to just move the photos over to a computer, or even a cloud account, rather than the card, and save new pictures you create to the card. This would be done in the settings of the camera app, setting it to save the images to the card.