im very new to this forum
can anyone tel me y do companies get listed in the stock exchanges though they cannot directly sell their shares in the secondary market.??? they have to pay money to the stock exchanges for their listing...

Perhaps it is because this is the way that stock exchanges get their revenue. They can't just list your company and then when you sell they won't have anything? They have to spend for advertising, their site maintenance and others. They also have to make profit, too.
I don't know if I am completely correct, though but this is how I see it.