Angelica and Lorenzo, 

You selected the important points from the article.  I especially like that you included the comment from his cousin that motivated Alfredo.  That seemed to me as well a turning point in his life. 

The first sentence needs an article. It should be "a former illegal immigrant." 

You need a period (.) after "immigrant" because it is the end of the sentence. "Cross" should be past tense (crossed). 

After "camper," you need a period (.) Be careful not to end sentences with commas (,). If that is your habit, you should break it. 

"Take a decision" has the wrong very and the wrong tense.  It should be "made a decision."

"Decision" is misspelled. 

"Start" has to be past tense (started). 

"In this time" should be "At this time" (English prepositions are difficult). 

"US" is incorrect. "U.S." is correct. 

Alfredo Quiñones was former ilegal immigrant, about twenty years ago he cross from Mexico to USA and became a migrant farmworker.

He picked cotton, tomatos and cantaloupes, and lived in the fields in a broken down camper, one day his cousin told him he would be a farmworker for the ret of his life, he take a decicion to change his live.

He start to study English at a community college,but quiñones developed a passion went on to harvard Medical School, in this time to study he received his US citizenship.

Today he is a neurosurgeon and professor at Johns Hopkins University.