An atheistic funeral?

My father in laws funeral was today. One of the pastors there preached about hell and fire and brimstone and yadda yadda yadda. It occurred to me that, growing up in a moderately religious family in Appalachia, I've never been to a non religious funeral. Even though (hopefully) I won't die for a long time, I don't want a religious funeral. I don't know what that would be like though. I want to put in my will that I don't want any religious rites, but how does a non-religious funeral work?