http://m.samsung.com/us/support/owners/product/SCH-I510RAAVZW The manual is at the site above. The best way is either plug into your computer and access the phone as a mass storage device. Or you could simply look in your settings to have pictures and videos and music go to the sd card by default via your settings. Again download the full manual and it will tell you how to do it.
Easiest way for me is to connect my phone to my computer via the USB cable and 'drag/drop' the files. Others use file manager apps available from Google Play.