How do I delete songs that i dont want any more off my sansa ipod?

I have some songs on my sansa ipod i want to delete and i cant figure out how…can any one give me step-by-step instructions to delete songs?

Also my screen on it is all messed up bc my friend tryed to put it in her apple ipod speeker things and now i can still read it and stuff but i cant watch a movie on it, or look at pictures. How can i fix that? Will taking it apart help it any bc my dad wants to take it apart and try to fix it. ( He is good with electronics so i trust him not to brake it )

thanks