Try these steps and tell me which part of it doesn't work and where you can get upto.
1 Install Unetbootin to make bootable USB unetbootin.sourceforge.net
2 Choose the version of Linux, in this case Ubuntu, and the version of it you want. Choose wisely between 64 bit and 32 bit, but we recommend 64bit generally.
3 Wait for it to make it and of course remember t plugin your USB
4 Reboot your PC
5 Go into your BIOS, usually f12 or f2 or something like that....it should say somewhere :)
6 Go into Boot order in the menus
7 Move USB to the top of the boot order
8 Exit saving changes
9 Should come up with a menu and choose Try Ubuntu without installing , or you could install directly but I prefer to use the Try Ubuntu without installing
10 There should be a file saying Install Ubuntu and click on that
11 From there on, read the steps carefully and all should go well
Hope this helps and of course Good Luck! :)
It should say an option to not to install updates