I am taking an online course and have no instructor to help me....HELP!

Suppose the random variable X has the pdf f(x)=e^(-x). Let the random variable Y= X(1) + X(2) where X(1) and X(2) are random samples from the above pdf. *Note: the 1 and 2 that follow the X's are in subscript form.

1) Find the pdf of Y.

2) What is the expected value of Y?

3) What is the probability that Y will exceed 1?

I do not even have a clue where to start or I would put out what I think.

Thank you!