I'm having a miscarriage scared and confused?

I just found out today that I am having a miscarriage. This was my first pregnancy. I went to the doctor after spotting that turned into a little bit of blood. It was confirmed that there is no heartbeat. Now I'm bleeding like crazy and have bad cramps. I will be having a dnc tomorow, and I'm nervous. Am I going to bleed after the dnc? For about how long? I think I did everything right during pregnancy. I wish I knew what went wrong. I guess it was God's plan eventhough I don't understand.