Who is a Muslim? A Muslim by broad definition is one who submits his or her will to the one true God. A more detailed definition of a Muslim is one who believes in one God and also believes that Mohammad (peace be upon him) was the last messenger sent to guide humanity towards the righteous path.
If you are convinced that there is only one God, and that Mohammed was His last messenger, then you are already, in terms of belief, a Muslim. What remains is for you to act according to that belief. The first requirement is for you to announce your faith. You may do so privately, and later on in the presence of other Muslim witnesses. The confession is simple. Say the following words with confidence:
“I testify that there is no true deity except God Almighty (Allah), and I also testify that Mohammed (peace be upon him) is His messenger”
After this declaration of faith, you should try your best to learn and follow the commands of God (Allah) through His last book, the Quran, and the teachings of His messenger Mohammed (peace be upon him).
Once you accept Islam, Allah forgives all your previous sins, no matter how many or how big they may be.This is a huge blessing for new Muslims.