I was asked by an atheist if Noah was white how did we get all other skin colors in our world?

I know the groups divided by language after Babel but i want to give him a good answer.

I'm sorry, but there is no "good answer" for this question.
First, let me point out that the Bible doesn't say that Noah was white. That may be what people depicted Noah as in paintings because they have never met someone who wasn't white, but that doesn't mean he was.
Secondly, I would like to ask you this question:
What does the color of people's skin have to do with the topic of whether God exists or not? It sounds like this person is just trying to trip you up in questions that he knows there is no answer for. If he/she is truly curious for an answer, then don't be afraid to tell the person that you truly don't know and there is no way of telling. Otherwise, I would be careful about trying to answer questions that cannot be answered.

Hmm... That is a good pondering question.

I doubt Adam and Eve were even white... We are just so prideful that is what we automatically assume, that everybody looks like us! HA!

For all we know Adam (made of dirt) could have been dark complected and Eve (made of a rib) could have been light complected. I just know My God is big. If I understand everything that God has done, than He wouldn't be God... I would be "all-knowing." I think it is a-okay to still have questions. It proves God is God!

Just keep loving God and loving people Mitch! You are doing great buddy!