Dear TOEFL in Iran:
The Test of English as a Foreign Language (TOEFL) is used by the colleges and universities in the US, Canada, and other countries to assess a candidate's proficiency in the English language. The TOEFL is given around the world in as many as 180 countries. You may wish to read the following document:
At the present time, it seems that the TOEFL is not held in Iran, but you can select one of the neighboring countries for taking the test.
For more information, visit the official TOEFL website:
Here you will find information about preparing for the test and for taking the test. Good luck!