I have recently puchased a 300E. I also have a flash card, a reader writer and an adapter.
My computer doesn't seem to recognize the reader when I plug into the USB slot.
Do I need a program to work with these tools?
Please read your manual. It thoroughly explains how to use the card that comes with the machine. You should be able to use one of the slots in front on your computer for card readers also or get an adapter for around $12.00.
Sewing World commons has a whole section under the Janome tab concerning this same subject.