In yahoo games, chess,on what basis u r giving marks, when we resign, when we loose?

When you win, your rating increases. When you lose, your rating decreases. When you draw, your rating becomes closer to your opponents rating. For example if you (a 1200), draw with a 1300, your rating may become 1215 and your opponent's rating 1285. Also remember that the greater difference between ratings, the bigger the magnitude of rating changes in upsets. I don't know, however, the exact formula that Yahoo Chess uses.