The word "Muslim" means one who submits to the will of God, regardless of their race, nationality or ethnic background. Becoming a Muslim is a simple and easy process that requires no pre-requisites. One may convert alone in privacy, or he/she may do so in the presence of others.
"Do you not know that accepting Islam destroys all sins which come before it?" (Saheeh Muslim)
If anyone has a real desire to be a Muslim and has full conviction and strong belief that Islam is the true religion of God, then, all one needs to do is pronounce the "Shahada" with sincerity and conviction, the testimony of faith, without further delay. The "Shahada" is the first and most important of the five pillars of Islam.
Upon entering the fold of Islam purely for the Pleasure of God, all of one's previous sins are forgiven, and one starts a new life of piety and righteousness.