Is your idea something brand new, or is it something already on the market that you've done better? Either way, you either have to go into business to make it and sell it, or find someone who will do all of that and pay you along the way. The latter is licensing.
The first thing I did was find the companies who make gloves for little hands. I bought their smallest pair and measured the placement of the thumb and then had my son see if he could put them on. As usual, he couldn't put them on so I did as much research as I could about the company to see if they are a prospect for a potential licensing deal.
If I thought they were, I called and asked to speak with someone in their product research department. The people in this area of the company have all picked up the phone and been willing to talk and share details. In all of my cases, they gave me the name and direct phone number to the person I needed to speak with about licensing our idea. Once these conversations started, the signing of NDA's was easy as pie and we were off and running.
If your not willing to make the initial contact with the companies you hope to be business partners with, there's not much hope that they'll call you. Pick up the phone and introduce yourself!