Setup Google Site Verification Code

How do you setup the Google Site Verification code?
https://www.evernote.com/l/AVw3EpJYpOpLSpFq-R5_QN3haarNw0UAbIE

I am a little disappointed that when useing the wizard it does not explain this in more detail. PLEASE ADVISE? When I look up the example on your website it is not the UA code. So what is it and where do I get it? Do I need it?