Sorry if this is a bit vague, I am not an expert in this area but I have a few tips. You will need to start with installing a few things:
1 - you will need the drivers for your device. A good place to start looking for these things is madwifi.org.
2 - you will need some form of network manager. Ubuntu has one built in, but there is another one (I forget the name of it) that works too. You can find some information on it at the madwifi site.
Another good resource of information on the wireless networking for Linux is madberry.org. This site also provides a (different) set of drivers and utilities.
Then there will be some tools you will need, if they are not installed. The tools will provide commands such as iwlist, which will you will use at the start to see if your wifi port is seeing access points, etc.
There is no reason you can´t get wifi working with the command prompt. You may need to ´build' the interface and then enable it with ifup, etc to bring it on line. Once you have it working with the drivers, you can add it to your network/interfaces and it should be permanent.
