A molar pregnancy for me was very hard to understand at first as well considering I was only 16. It is where you either have an egg where it empty (nothing in it) that unites with a sperm, but then it dies, but your body still is saying you are pregnant and the other way is if you were to have twins but something goes wrong when they are uniting and they split and do whatever happens and then your body also says your pregnant but not. I had the pregnancy where it was called a complete molar pregnancy where all that happened was I had an empty egg. My body kept having the symptoms nausea, gaining weight (just from the fluids building up in my stomach), and not feeling well all around. The only way they can for sure know you have a molar pregnancy is if you have an ultrasound and there is just a grape clustered looking thing there and no baby. So basically it comes down to I had the fetal stem growing but no baby. It was hard to understand this all myself and I still do research on it. Because my chances are higher the second time around and that is why I am worried for my ultrasound that I am having today. But another point I was going to make was that I read that some people don't know they have had a molar pregnancy until later, because it takes so long for things to happen. I am not real sure on that, but this is one thing that is on a rapid increase and I think all woman should know about it.
And no don't real scared to ask me about this, because trust me I have had to try to explain it more than once:p.