There are web sites who pays you per click on the advertisements. Most of the web sites are fraud but some really pay . The clicking job is not worth as compare to time consumption.
First you have to find a genuine site and get your self register there with email address. They send daily 10 to 20 ad through email. Open the email and click the link provided in an email for asked time (usually 20 to 30 seconds) to get paid.
You need to click at least 400 to 1000 links to earn $1 and most of them have pay out of $2 to $5. It takes about couple of months to reach a minimum pay out. If the site is a fraud then after spending so many time nothing achieved. If the site is genuine even then I think its not worth to spend time to earn only some pennies a week .