SIN

I went to church tonight and the Pastor spoke about taking God's name in vain. He said that it is a sin to take God's name in vain. There are so many sins, that just thinking about it makes my head spin. I have some questions though, such as : Is it a sin to look at nude pictures on the internet? Is it a sin to think about the pictures that I just saw on the internet last night? Is it a sin to dream about those nude pictures ? Is it a sin to want to look at those nude men again tonight? Is it a sin to dream about those pictures again tonight? Is it a sin for an unmarried woman to have lustful thoughts for an unmarried man? Because if it is, I am gonna be in SERIOUS trouble.....