My sincere advice to you is to start understanding the Holy Quraan little by little (like only one to three verses every day). You will understand the religion very well insha -Allah.
If a Muslim makes 5 salaath daily on proper time, fasts in the month of Ramadhaan, pays zakaath 2.5% on his savings once a year and goes for Hajj once in his life if he can afford the journey, it is very much expected that he will win Allah's Mercy, and any one who wins Allah's Mercy, will enter Paradise. If such a Muslim has sins then it depends on the type of sins. For e.g. he tried to fulfil the rights of Allah but he was not good with people. People have great many rights on each other. Our worshipping to Allah has two parts:1. We must pay the rights of Allah and 2. we must also pay the rights of the people.
If a Muslim deprived some people of their rights, then it is very much possible that on the Day of Judgement all of his/her prayers, fasting and other good deeds are given to the people in turn of their rights. In the end this Muslim will have nothing to give to people in exchange for their rights, then their sins will be put on his/her shoulders. So in the end such a Muslim will go to Hell. Allah knows when he/she will be taken out from Hell.
That all means that we human beings are not free at all. We have to be very careful at every step. We must do lots of zhikar and du'aa to be protected from Hell. In a hadeeth we are advised not to wish for high levels in Jannah. This is because the Day of Judgement is so much hard that the Prophet of Allah (alaihim salaam) will be shaking with fear. We will have to cross a bridge on the Hell Fire to reach Jannah, so the first place to come is Hell. Therefore we must fear a lot, the more we fear, the better it is.