Underground Writers Network Forum A Question

I just finished the first draft to my first novel.  Right now I'm trying to work on editing it, but I have no idea where to start.  I know I need to write a prologue to give more background on the characters.  I've got a couple books on self editing and I've been reading those a little bit, but sometimes they only give me more questions.  I also have my English teachers in my head telling me the proper way to write, even though some of it contradicts each other.  Can you use both past and present tense and if so in what cases?  Umm I'm just a bit overwhelmed.  Any suggestions or advice would be greatly appreciated. 

you have to learn to decide what advice has value and what is not. if you know someone willing to review the manuscript and give an honest assesment would be the ideal-this is very difficult for some. have you posted chapters on here? you might get good feedback that way. have you ever taken a creative writing class? this can at least get you read by an outside audience.