Suppose I'm standing at the corner of a street doing some pie-throwing practice. You walk around the corner and get a pie in your face. Assuming you believe that it's reckless of me to be practicing pie-throwing in a public place where someone might come around the corner at any moment, it makes sense to say that it's "my fault" you got a pie in the face. We might say that I'm morally responsible for the pie in your face.
Now, suppose that the reason you walked around that corner is that your brother had asked you to go out and buy a newspaper. (Do people still buy newspapers? Ok, maybe he asked you to go out and buy a chocolate bar). He had no idea that I was out there doing pie-throwing practice, but if he hadn't asked you to go out and buy the chocolate bar then you wouldn't have walked around the corner and you wouldn't have got a pie in the face. Most of us would say that isn't your brother's "fault" that you got a pie in the face, in the same sense that it's my fault that you got a pie in the face, but it is true that he was involved in a series of events that ended up with a pie in your face. We can say that your brother is causally responsible for the pie in your face.
Of course, moral responsibility is a tricky issue and is completely dependent on your beliefs about morality. If I set up a pie-throwing robot at the corner of the street, and she throws a pie in your face, most of us would say that she's causally responsible but not morally responsible for the pie in your face: robots can't make choices of their own accord, so we don't generally say that they're morally responsible for their actions. But what if, say, a 5 year old child who throws the pie – is she not morally responsible because she's too young to know what she's doing? What about a 12 year old child? And some people would even argue that no human really has "choice" in a morally relevant sense about what she does, that all our decisions are shaped by factors beyond our control: those people might say that, in truth, nobody is morally responsible for their actions.
Still, I'm sorry about all that pie on your face.
Read more: The Stanford Encyclopedia of Philosophy on Moral Responsibility