How can I authorize my Samsung Tablet. I already have my eReader and PC authorized but need to add my Tablet as well

1. How can I authorize my Samsung Tablet with Digital Editions? I already ave my PC and Kobo eReader authorized  but need to add my Tablet as well. I am not always at my PC or near my PC

2. How can I import and export eBooks into Digital editions so I can access them all through my eReader?