Internet investment. Just a SPAM.

Recently I've received a lot of e-mail from Africa saying that they have unclaimed money in certain bank and ask if I can help them transfer that money to my country. Another e-mail is about some sick person in hospital that needs financial support. Then there's lotto e-mail that says I've won some. How do I get rid of this e-mails? I almost invest in Swisscash yesterday, until my friend told me that they're also cheating many people over the internet. Oh gosh... What should I do? I desperately want to earn extra income, but how can I do that if most of the internet stuff are SPAM?