Iran is one of the oldest countryies with history more than 2500 in the worldyears of history. Iran is one of the oldest countries with more than 2500 years of history.

Rewording to sound more natural.

Iran is one of the oldest countryies in the world with a history of more than 2500 in the worldyears. Iran is one of the oldest countries in the world with a history of more than 2500 years.

One of many instead of one of one.

It has a lot of historical buildings like Persepolis It has a lot of historical buildings like Persepolis

a lot of many instead a lot of one. Is Persepolis a building or a city?

iran iran

Iran. (Capitalize).

Hi every one, I'm one of the people infrom Iran and now iI want to speaking (or talk) about Iran. Hi everyone, I'm from Iran and I want to speak (or talk) about Iran.

Minor corrections

Hi every one, I'm one of the people ina native of Iran and now i want to speaking about Iran. Hi every one, I'm a native of Iran and now i want to speak about Iran.

I cannot say why "one of the people in Iran" sounds funny. You could say I am in Iran. We know you are a person (people). To speak (infinitive) or to be speaking (action in process).