Linux Wi-Fi Problem

I have installed the latest version of Ubuntu Linux on my laptop a while back, but I am having problems setting up my Wi-Fi. I have followed various tutorials around the internet, but none seem to work for me. (Or I am a complete idiot.) The one I have looked over the most is this one. I have tried to use Ndiswrapper with the driver for my Dell Inspiron 5100 laptop, but it will not work. Can anyone help? If you need any more info, just ask.

sudo apt-get install wifi-radar

you need to connect via ethernet or whatever, if you cant directly connect you can download the wifi radar package of the net and save it on usb and transfer to your laptop

also, is this a new 5100 since Dell model numbers rarely make sense: if you buy a dell inspiron 6000 now it will be more powerful than 5 years ago although they have the same model number

Try installing NetworkManager, maybe it will solve problem automatically
You can as well try system-config-network and do some configurations manually ;) (some people like that)