Advertising companies/websites

Hello, I would like to put some advertising up which other people will pay me for to advertise their product and goods.

Could you please tell me how to do this?

Go to google?
They pay like $1.50 a month for your website to put their ads on there.
Depending how many people see the ads of course.
$1.50 = 100 people a day
$2.00 = 200 people a day
$3.00 = 400 people a day

so on...
etc.
(not exact though)

Yes I have adsense up, but I wanted to put people's personal ones.

Can somebody tell me how to do this please?

Anyone?