Picky Eater Trying New Things?

I have a 5 yr old little girl, who is very set in her ways. She'll only eat Chicken Ramen, Spagettios, and Ravioli (from a can). She'll eat chicken strips, or bologna snadwiches, but only on rare occasions. When it comes to things like candy and fruit snacks it's the only thing she'll eat (if she knows they're in the house). I don't pack her lunch, so they try to make her eat at school, and still aren't having much success. How do I get her to try new things without being mean, or making it seem like a punishment? I've told her she has to sit at the table unless she takes one bite, and she will WILL sit there all night long. I'm starting to get concerned about her health. Help Please