How to put google Ads

Hi,
While reading google API terms and conditions, I have come across that,
I have to allow google ads on my web page.

My questions here are
How do I put google ads on web page or allow google to put ads?
Is there any method in google api to do this?
Can I choose what type of ads I can allow?
How many ads google will put on my web page and can I specify place in
web page where ads will go?