Are you familiar working with terminal? If so do you have a rootsh installed from application manager? After you install rootsh you can open terminal and type sudo gainroot and you hvae root rights.

If you are familiar with using terminal you can navigate to the place where you downloaded the .deb file you tried to install and type dpkg -i and add the name of the .deb file and hit enter. This way it will probably give you information of why you can't install liie missing dependencies.