You can do this using the mass storage mode when connected to the computer.
Open the "my computer" folder on the PC. Plug your BB into computer. Another drive should pop up under "Devices with removable storage". Double click this icon and then double click the Blackberry folder. Select the folder you want and then drag and drop the files you want into that folder.
Like Kasi said, Mass Storage Mode is the easiest way. But you can also do it from your device if you don't have a computer available. I'm guessing that you have your pictures and music on the device memory and want to move it to the media card memory. Open the media app, press the bb key and select explore. Choose the device memory and navigate through the drive until you get to your pictures folder. Highlight the picture that you want to move, press the bb key and select move. Now select up until you get back to the screen with your drives, select the media card and keep opening the folders until you get inside the pictures folder. Finally press the bb key and select move here. Just repeat this for all of your pictures you want to move. You can do the same with the music but select the music folder for each drive.
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