How does the stamp fee shared for international mail?

For example if I send a mail from one country to another country, how does the destination country post office gets for sending my mail to th e local address?

The Universal Postal Union.

The link below will take you to the manual that handles postal payments

What a great questions ! Thumbs up.... I guess the answer is that there has to be some kind of reciprocal business agreement....

I am just guessing with this answer, but it is probably close. I'm thinking that the U.S postal service uses the extra money that you pay for international mailing to pay the receiving country for delivering your mail. For example, if you are sending a letter to Canada, you might have to pay an extra 50 cents in postage. The U.S postal service may allocate 35 of those cents to cover the expense of getting the letter to Canada, and use the other 15 cents to pay Canada for delivering the letter locally.

What? This is awfully hard to follow.

Are you asking how the destination country is paid for handling your mail?
There are postal conventions between countries that cover this. In some cases it is a reciprocal agreement, in others there is a direct payment. But the extra costs of getting mail from country A to country B are covered by the out of country surcharge on letters and parcels. That's why it costs more to send a letter overseas than to mail it across town.