As what others have said,,,, you need a memory card reader. You can buy them online from any place that sells electronics, or go to
Best Buy, Wal-Mart, Target or any place like that. They are a small device that sells from $5-20 and plugs into the USB slot on your computer (most new computers now come with a memory card reader built in). The readers are a bit different. Make sure you get one that will fit the kind of card that fits into the Digital Frame. You will find 5 in 1, 8 in 1, 12 in one, etc... Just about all will read SD cards since that is the most popular these days. But there are other kind of cards (CF, Memory Stick, xD and others).
You then put the memory card into the memory card reader and plug the reader into your computers USB port (same place you'd plug in your camera and probably your printer (unless you have a old printer). This will let you use the memory card like a floppy disk or blank CD.
Open two explorer windows on your computer. In one window go to the file that your pictures are. In the other window open the blank memory card folder. You can then drag the files from your hard drive to the memory card.
Its actually a very simple process.