I keep getting at least six emails in my spam folder from Nigeria, China, and other places. How can I block?

The messages say I have won lots of money and I should open the attached file and send them all of my personal information. One even asked for my SS number! Also, many of them supposedly come from the FBI. How can I stop this? The messages are all in very poor English with many grammatical, spelling, and punctuation errors -- without any place to opt out and get my name off their lists. Can you help? Thank you.