"Blaming" someone for a bad situation means saying that they caused it. You can blame someone for a mistake, a bad decision, an accident, etc.

Are you going to keep on blaming your parents for all of your problems and flaws? At some point, you need to take responsibility for your own life.

If someone has caused something good, you don't "blame" them for it. Instead, you "give ___ credit for ___" or "attribute ___ to ___."

Mandy gave me credit for being the one who came up with the original idea.