Catholicism and christian church?!?

so when i was a baby i was baptized as catholic. ive never been to church and my family isn't religious at all. i was only baptized because my dad came from a religious family. so after 13 years i have realized i want to go to church again. i need help though, how do after 13 years of not believing can i start to now? and whats the difference between catholicism and christian? i really want to do this and i want to take it seriously so please help me