WE files are also known as WorldEdit schematics. Diwnload the Printer.we file as it is named, making sure the extension is in fact .we. Put the file in a folder called schems in your world folder (the one that we will be putting the printer into).
First, make sure you have WorldEdit, and a recent version at that (the github link is always pointing to the very latest version, 0.6 is slightly outdated already):
http://forum.minetest.net/viewtopic.php?id=572
(I might be a bit biased, but you should have this anyways because it's so darn useful)
Next, you can find out how to use this mod by reading README.md. I tried to make the documentation as simple to follow as possible, but ask if you have any questions. In short, many things are done with chat commands.
Use //pos1 to set we position 1 to the location of your player. Optionally, at this point you can use //allocate Printer to see how much space it will take up when we import it later. The corners of the region of space it takes up will be visible as black markers. Now, if everything is fine at this point, use //load Printer to put the actual schematic as real nodes into your world. It will be placed at WorldEdit position 1, or at least one corner of it.
I recommend doing it in a new world first, since if you're not careful WorldEdit is still a very powerful tool and can cause massive damage.