Nook Reader

I downloaded the Nook reader on my iPad, but I had some books in the "documents" folder on my Nook device. How can I get them into my Nook App on my iPad so I can read them??

Let me clarify if need be. I have a series of book I bought for the Nook from B&N. A friend has a different series. We downloaded the files and e-mailed them to eachother, and provided the info required to unlock it on our Nooks. Now that I have an iPad, I would like to get those files she e-mailed me so I can use my iPad with the Nook reader app on it......