I received an E_Mail claiming that i have wone some money from YAHOO LOTTO.is it true or it is just a spam.?

100% SCAM. Yahoo doesn't have lotteries or cash giveaways. If they did, you can be sure there would be a LOT of advertising for it all over their web sites. Just delete that email, and any others like it that you are likely to get. DON'T reply to it, and certainly DON'T click any links in it.