The first step is to open the folders, in your cell phone, where the files that you want to transfer are located. It varies from cell phone to cell phone and, in some cases, files may be hard to find. However, here are the most frequent ways to find your media files:
In the case of the Nokia 6300 shown here, I pressed "Menu", "Gallery", "Images" and selected an image I wanted to transfer. On a Verizon cell phone, I would have retrieved my media files by selecting the "Get it Now" menu and then specific sub-menus like "Pictures & Videos" then "My Pictures" or "My Videos". In most cases, you can also select multiple pictures by pressing the "Options" button and selecting "Mark" or "Mark all".
(Illustration: The Nokia 6300.)