Ubuntu from flash disk

[ex-wirecutter]

I am trying to install Ubuntu on a flash drive. I have downloaded the instructions but get stuck at " unmount ".
Having typed fdisk-l it shows my flashdrive as /dev/sda , and gives the correct memory size but when I try the unmount/dev/sda1 command it says it can't find it.
The instructions also mention U710fix.tar , what is that ,do I need, where do I get it ?
Absolute beginner

[freesitebuilder]

You may get more info in the Absolute Beginners forum, as more people will see it there. Welcome to the forums, anyway!

[ex-wirecutter]

Thanks , just shows what a novice I am , I thought I was on the begginner's forum.
Will re post query there.

[njparton]

It's actually umount, not unmount :)

Got me for a while too!