Have a computer and an internet connection? That's enough to begin with earning cash online. To receive your payments, you will need a payment processor account like Paypal or Payza.
Below there are some 'paid to click' sites where you can earn money just by creating a free account and watching advertisements. For each click on the ads, you will be credited. You do not need any investment to earn, but if you invest to gain a premium membership, you can surely earn more.
Sign up with these sites, click ads and earn money.