Slave trade and European Industrial Revolution

I'm going to be honest, I don't remember much from middle school history about the slave trade. I know that people were taken from their homes in Africa to be shipped off to different places in the world to be slaves. The chiefs of African tribes would either -I can't remember- a) sell their own people to the slave traders for profit, or b) kidnap people from other tribes and sell them. The conditions on the boat were terrible. They barely had any room to move, since as many people as possible were crammed into large boats. Many people became ill with disease from the horrendous conditions, and died on the boat. They were tossed overboard so as not to stink up the boat. They were treated terribly even off the boat, and were chained to one another to make sure they could not escape. Once they arrived at their final destination, they would be auctioned off to the highest possible bidder. Families were separated, and many buyers could care less whether they were or not. Usually, the strongest, fittest men would sell for the best price, since they could do the most hard labor. I don't remember when the slave trade started, but would like to know. I'd be curious to know who thought up this "wonderful" - sarcastic- idea to treat people this way. Also, I'd like to know how they could treat people this terribly - what motivated them?

I do not remember that much about the industrial revolution in Europe either. I know that people started inventing machines - machines that could do work. These machines and contraptions started taking the places of people who worked, causing them to be without jobs. The companies realized that they would save quite a bit of money if they had machines do work. They did not have to pay them, like they had to pay the workers. That's pretty much all I remember. I'd like to find out what these people did once they were fired? Also, when did this take place? It might have caused the people to be unhappy, making them more likely to revolt.