Aleum and Xiang,

You've gotten the key points of the article. It could use a little more detail, for example about his work as a community organizer in Chicago.

-African-American is the correct form.

-"Obama has studied at Harvard University after he studied at Cloumbia University" has the wrong verb tense. It should be "simple past tense" (Obama studied") not "present perfect" because you specify a past time. 

-"Columbia" is misspelled. (It's easy to check spelling on the computer, and you should always do it). 

-There should be a comma (,) not a period (.) after "In 2004." 

Barack Obama is the 44th President of the United States of America.

 

He is the first afican American to be President. Obama was born in Hawaii in 1961 to a black Kenyan father and white American mother. Obama has studied at Harvard University after he studied at Cloumbia University. Obama's charisma, intelligence, and powerful speeches have made him extremely popular with Americans.

 

In 2004. Obama was elected as a U.S Senator. He supported legislation on conservation, energy, immigration and honest leadership. He won the Nobel Peace Prize for his "exraordinary effort..