What do I do with Devolo ?

Hi
I have just bought a couple of Devolo LAN 200 home plug units on Ebay.
Do I have to connect one unit to the router and the other to my Humax for it to work or is there more to it than that?
I am not looking to create a network between computers simply to allow the digibox to access the internet.
One of the units came with several passwords, which I found a bit worrying.
regards
phil