How do I get rid of all of these Scam emails?

A little over six months ago, I was winning the UK lottery about three or four times a week. Now my email is bombarded with those every day along with business proposals where they want me to cash checks for them (yeah right). I am getting approx. 150 of these a week. Does anyone know how they got my address. I'm thinking it's from Monster.com or other sites I have visited. My question though: Is there any way to get rid of these and if so, how do I do it. I'm just not getting them from a few people. These are different emails coming from all over. All scams. How the heck do they get away with this. I guess it's kinda hard to catch these people. I saw a show on dateline about this and a lot of them come from Nigeria. I've been getting them from there as well as London and China. I just won a bunch of money from Queen Elizabeth's Foundation. How are people still falling for this when it's all over the place. I can understand people getting conned when it first started but come on! Help!

The location to block spam emails in under the "Options" link.
1. Click on the "Options" link in the upper right of your yahoo mail page.
2. Click on "Spam Protection", fill out the form and click the "Save Changes" link.
Once you have this set up, each time you see spam or mail that you want to block, check the box next to it, go to the top of the email list and click the "Spam" button.

Note: Every message you report trains your Spam Guard filters to work better for you. The messages you select in this way will be deleted and reported as spam.
The senders of the messages will be added to your "Blocked Addresses" list.