Are you running Windows Vista or Windows 7? If you are, you are not suppose to install the CD software on your computer, you need to download it from the Brother site.
Make sure your reader is plugged in and you have a card in the slot.
Can you open up the PED Basic software from your Program Menu (or if it's like mine, it installed a shortcut on my toolbar, I click that)?
If you already have the PES files on your computer and you can open the PED software, click on the little file folder at the top of the window that opens up.
Click on the folder where you have your embroidery designs, click "Ok"
They should now show up on the left side of your screen. If they don't, make sure your files are in PES format and that they are all unzipped.
Once they are showing up, click on the one(s) you want to put on your card, then hit the arrow button in the middle of the screen.
The design will now show up on the right side of the screen.
This will transfer your designs to your card. It will warn you that it will overwrite all existing designs on the card, (like when you erase the pictures from the memory card on your camera). click ok, or continue or whatever it is.
It will tell you to wait a minute, then it will pop up that the transfer is complete.
Take the card out of the reader and put it in your machine.
I only have a Brother 270D, but on my machine, when the card is in and the embroidery unit is on, there is a little symbol that looks kind of like the memory card, I click that and it will show all my designs that are on my card.
Click the one you want to stitch, and you should be good to go.
When you have all the designs on the right side you want, click the arrow thingy on the bottom of the right side of the screen.