yes, you have to write in xterminal, when you have gained root access.

For rootsh, you can try to install it manually.
-- Download the file http://repository.maemo.org/extras/p..._1.5_armel.deb
-- Once downloaded you have to copy this from your PC to n900, lets say copy it to /home/user
-- once you have the file in n900. do
cd /home/user
dpkg -i rootsh_1.5_armel.deb
And it will install the rooth, after this you type "sudo gainroot".

I am not sure, but try to download and save this file directely from your phone. might be it will work.

Good luck, search forum, if you are stuck. or we will see tomorrow.