What are the noahide laws according to Judaism?

where can I find them in the Bible? because rabbis say those laws were given to the sons of Noah but I don't understand a person who follows those laws is Ok.. but someone who disagrees with them is not Ok for the next world.. I am lost where are those laws? and why do non-jewish need practice them? if according to judaism there is not obligation to convert to the judaism.. a rabbit told me if the other people don't find those laws. they are lost? why? so to adopt the noajide laws is like being part of judaism but not totally?