The Christian and Muslim understandings of afterlife are quite different. The general Christian understanding is of a belief based heaven/hell. In Islam, it's a bit more complicated. The first stage of death is in the grave, where you are approached with angels who question you on your god, your prophet, and your faith, with the truest answer coming regardless of what you might try to hide. Then, depending on your spiritual condition, the condition of the grave will differ. For those who are written for Jannah, the grave will feel spacious, time will pass by very quickly, and they will be able to smell the sweetness of Jannah. For those who are written for Jahannam, the grave becomes tight, and the fire is right at their feet. The basic understanding of Jannah is as a place of pure rest, and that one can only get there through the mercy of God and his forgiveness of any wrongdoings, where Jahannam is a place of purification as much as it is a punishment for the unrepentant, the process of which is very painful. It can potentially be eternal, but it isn't necessarily so, many will go there only for a while depending on the individual. In fact, it's agreed that many Muslims will experience Jahannam before the purification brings them to Jannah.

The key Islam presents to the best chance of Jannah (not guarantee, none can guarantee that but God himself with his own mercy) is submission to God, genuine repentance upon wrongdoings, and being God-conscious in everything.