How do i thread the bobbin on my necchi 539

Question

I have a necci 539 sewing machine. I am brand new to this whole sewing business. My bobbin was loaded for me and I was sewing until I figured out that my bobbin was out of thread. I put another bobbin in that was already threaded but I cannot get my bobbin thread to catch with the top needle. I am so frustrated right now...any help out there?