I've had a look for a good guide and this one seems to be as good as any:
http://www.howtogeek.com/51873/how-to-setup-software-raid-for-a-simple-file-server-on-ubuntu/
Why don't you take a look at that and let us know where any confusion is, people can then help you though those specific bits.
Just as a note, if you'd rather do the partitiong bit through a GUI then you can do all the steps they do in the 'partioning discs' section via gparted, which is a standard part of the install for Ubuntu. It might be worth having a look via gparted anyway just to get your head round the disc / partition naming, coming from a Windows background it might seem confusing but is really no different from the device ID scheme used under windows...