How to make a bulb?

I have tried to make a bulb which should be a spotlight and gives rays in a form of cone. When i turn it on it should have nice yellow color and produce that rays. I have tried it but my rays wont go at a specific point, and the sphere which i think is a good form for a bulb wont light.
I would be grateful for any advices.

OK, from what I read in your post, you need to have a light that switches on and off… That’s rather simple to do, if you’ve read the lighting section of your Red Book. Making the floodlight look like it’s on is just as simple. What you should do, rather than render the floodlight normally, render it with lighting turned off, and perhaps your intended yellow color. Making the light corona, if you want one is a bit trickier, I suggest you find a tutorial on that.