Yeah, basically you repent. But it's not that simple; you have to be honest and sincere in your repentance, promising to Allah that you'll try your very hardest not to ever commit that sin again. With repentance, you can't take advantage of it for example and say "Oh, I'll commit this sin and repent later."
Take it easy, bro', one step at a time with your new faith .
If you have sinned and sincerely and genuinely have regrets and guilt about what you have done, then repent and ask for forgiveness from Allah. InshAllah' .................... Allah sees all and knows all even the deepest secrets in your heart..........