If you just executed the "sudo gainroot" command then you are normally in /home/user directory. You can enter into the MyDocs from there by typing "cd MyDocs"

One more note that if you did unzip the files on your host computer (Windows, Linux, OSX...) and copied them to your N8x0 memory card using the USB cable, you can copy them to the correct location (/home/user/MyDocs) just simply by opening File Manager in N8x0 and copy the files from the memory card to the top level in N8x0 directory tree (seen as "N800" on my N800 device). Therefore you do not need to "copy" them any furtner in Xterm... But you still need to change the files to executable with chmod command. After this you still need to copy the Host.desktop and Otg.desktop files to correct places as described in the WiKi. This can only be done with Xterm and with Root access.

I can understand that this is not exactly most user friendy... and I did not by purpose make step by step instructions what to type in Xterm. The reason is that this method does mess with the system files and if done incorrectly can mess up the programs (extras)... so if you do not know what the WiKi instructions are saying then this method may not be for you...

I just hoticed that Konttori has posted similar application that does the same thing, but without need to mess with Xterm. You may take a look at it.