How does one enter Islam?
One enters Islam by uttering the two Testifications of Faith with the intention to enter into Islam. The Testifications of Faith are “I declare that no one is God except Allah, and that Muhammad is the Messenger of Allah.”
One does not enter into Islam by just asking Allah for forgiveness. Ayah 10 in Surat Nuh means, “I [Noah] ordered you to seek a valid forgiveness from your Lord.” This means that Prophet Noah ordered his people to seek forgiveness by embracing Islam, i.e., by believing in Allah as their God and in Nuh as His Prophet.