Evolution?

Today I was in Drugs and Behavior. The lesson covered the nueron, which is this little complex thing in the nervous system that sends signals to the brain to make you sense things. I'm actually paying attention because it was interesting. With every slide, it made me remember how amazing God is that He paid attention to these little details which make the nueron work and then make me, and my fellow humans, work. How can anyone deny God created us if there are these little detail? How is evolution possible? Then my professor explains these nuerons are surrounded by salt water and since we are made mostly of salt water, we must have evolved from some salt water creature. I looked at her like she was stupid, sorry to say it, because that just didn't make any sense to me. First of all, what did that have to do with the lesson. Secondly, how can you spend an entire lesson explaining this little complex piece of the body and then say we evolved from something. Part of me wanted to raise my hand and say hey, can you explain this...I'm confused. That whole evolution thing does not make sense. Needless to say, I had a hard time focusing after that.