Questioning the Lord.

i have always believe in god, but my friend has opened up my eyes. she asked me a question i, myself, could not answer what so ever.

Her question was "Where did God come from, and how did he get his power?"

I just want to hear what people have to say. this is all bothering me so much. God has always been my belief, but what if he isn't real. what if when we die and i don't go to heaven and something else happens to me, then i won't be ready. i was so ready to go to heaven, but now what if that doesn't happen? I just wish truth would reveil itself.