If you don't know what is going on - then there is no reason you should be compiling your own version of Ubuntu.
Where and how did you get such an instruction?
To use Ubuntu
First download the .iso file for the version you want
Second burn it to a CD using a "burn image" facility (don't just copy it).
Third - boot the computer with the CD as the first boot device - and you'll be running Ubuntu straught from the CD (ie not installed on your hard drive).