If you're really wanting the answer.. it may sound stupid.. but I'd pray about it. I'd say something along the lines of "Jesus, God... I don't know if you're real or not, but I'd really like to know. Please give me a sign as confirmation." I'd definitely personalize your conversation with him so it's authentic, cause you won't receive an answer if it's not from the heart, if you're just looking for some grand miracle. Also if it's truly from the heart then that would mean that you truly want to know & if you truly want to know. I would read at least 2 books from the New Testament along with some chapters from Psalms & Proverbs. You make a true effort to understand, you do these things & I know you will receive the answer to your question.