I got my boy interested in frisbee by first getting him to jump up and grab a ball from my hand on command, with a little running head start. Then I got him to chase a ball as I threw it, he loved chasing the ball. I transitioned over to a frisbee and had him interested in jumping up and grabbing it in his mouth then running around with it.
After establishing familiarity with a frisbee I started throwing it, but the concept was totally lost on him, I would throw it and he would run in the direction but watch the ground the whole time, then the frisbee would land somewhere next to him and he would snatch it up, this lasted a while and he wasnt getting the idea of looking up.
I ended up having to put him in a sit about 10 to 15 feet from me, then throw the frisbee towards him just like I would throw a ball to him. he had no problems tracking it in the air then and it was just a matter of time until he could catch it well. I changed it up again and instead of throwing it at him we faced each other about 15 feet apart and I threw it to forward and to the side so he had to take some steps to get over to it and catch it.
That was how we played the game for a couple months, then one day I threw it out far and he tracked it the whole way until it landed; I knew he was going to be able to catch it in mid air within a few more tries and he sure did! It was like a switch clicked when he first caught it out of mid air and he became addicted to frisbee. Now he is good at running and catching it. I can wind up and he begins his take off, then I throw it around 100 feet (not quite sure the distance), and he is already on the move, looking up to locate his target and adjusting to whichever direction the disc is heading, it all culminates in a sweet aerial catch and them him prancing back to me with the disc in his mouth all proud.
I keep the frisbee up on a ledge outside my door and every time we go outside he turns around and stares at the frisbee then at me, just aching to play... Even if its midnight and pitch black outside...