Can you put pictures that are on your computer on to an SD memory card?

Yes.

Place it in the card reader (you may also be able to use your camera for this, but if it doesn't work, don't blame us).

Find the card in My Computer. It will show as a removable drive.

Click on it. A window will open showing the contents of the card.

Drag and drop the images onto the file window. They should transfer to the card just fine.