What exactly is your problem then?

From your first post it seems you just wanted to check the contents of a folder. Does 'ls' not suit your needs?

You might also want to install mc (midnight commander). It's a nice console-mode file manager. Or use filebox (that's with a GUI).

If your problem is wanting to ssh from a PC into your N900 via WLAN, you have to make sure that your router/AP is allowing the connection.

Normally you have to look for the NAT settings (network address translation), so that you can instruct the router to forward packets directed to an ip/port combination (itś good to set your N900 with a fixed IP address for your home WLAN.. makes everything easier).