I like cubase!! I only just noticed this topic.
Install cubase. Then plug in the zoom to the USB. I think you have to install a driver. Plug some speakers, or headphones into the output from the Zoom, and your bass in the input. Open cubase, and go to Device Set-Up, and then choose the Zoom soundcard instead of the default direct X or whatever you have. You should be about set up now.
To hear bass, create a new track in the "arrange window" (I think it's called that). You have to right click on the grey area at the left, and click "create new audio track", choose mono. Click on devices at the top, and select "Mixer 2". This should now look like a mixer, with the one channel you've just created on it. At the top of this channel strip are two lines of text which represent the input and output routing. The output will default to the master bus, which is fine. You might have the change the input, though I doubt it as I think the zoom interface is mono.
anyway, on the channel strip is a little round button with a picture of a speaker on it. It turns orange when you press it. This turns monitoring on. Now you should be able to hear your bass! Highlight the red record button on each track you want to record. Press record on the transport bar to record.