Mara Selene

I have to explain why certain verbs use sein instead of haben for the formation of the Perfekt? and name some verbs that use sein instead of haben for the formation of the Perfekt!

I have to write a 250 word essay in German. You are going to talk about a trip you took to all four German-speaking countries. (Don't forget Liechtenstein!) Can someone help me i don't know what to write? Plus my german isn't good enough.