Hello, welcome to TurnToIslam, I really sincerely wish I could spend more time answering your question, to help understand, but as it is, I am short on time, but please check back, because I know there are many wonderful brothers and sisters who can help answer this question.
Allah said in Quran: 4 : 157-159
"And because of their saying (in sarcastic boast), "We killed Messiah Jesus, son of Mary, the Messenger of Allah," - but they killed him not, nor crucified him, but the resemblance of Jesus was put over another man, and those who differ therein are full of doubts. They have no (certain) knowledge, they follow nothing but conjecture. For surely; they did not kill him
But Allah raised him [Jesus] up (with his body and soul) unto Himself (and he alayhis-salaam is in the heavens). And Allah is Ever All Powerful, All Wise.
And there is none of the People of the Scripture, but must believe in him [Jesus, son of Mary, as only a Messenger of Allah and a human being], before his [Jesus alayhis-salaam or a Jew's or a Christian's] death (at the time of the appearance of the angel of death). And on the Day of Resurrection, he [Jesus] will be a witness against them."
In Islam, the Prophet Isa *Jesus* (alayhis salaam) was not crucified. As was mentioned, he was taken up into Heaven ALIVE and is still there awaiting his appointed time to return to Earth. However, one of the youngest of Isa (alayhis salam) companions volunteered his image as that of Isa (pbuh) and was crucified in his place and will be with Isa(pbuh) in paradise. Isa (pbuh)'s appearance was cast over this youth and he was crucified and will be given Paradise at a high rank because of it.
And for the people who say it cannot happen, remember that each Prophet was given miracles, and there is absolutely nothing Allah (GOD) cannot do. So therefore, it is possible, and it did happen.
Sorry could not help more...
P.S.
A Brief look at Isa/Jesus (AS)
And for anyone who wants to know a bit more... go to Tafsir ibn Kathir's explanation of that first ayah. I wish I could show you all, but Copywrite does not allow me to.
If you would like to go there:
Go to:
http://en.quran.nu/
Check the box next to Tafsir on the Header
Then scroll down to Surah 4: An-Nisa'
Under the header which says "Explaination for...." Scroll down the chapters until you get to # 138 The evil accusation the Jews uttered against Mayram and their claim that they killed Isa
If I have time later in the morning... i will try to find this and post it here, rather than give roundabout directions. But this IS a very good website, and I hope it will be of use to everyone insha'allah.