My homemade flute

Hey guys!
I couldn't wait till I got enough money to buy my real flute, so I decided to make
my own flute out of PVC. I found this old pipe in my basement, and decided it was perfect. Easy to work with, light and cheap! I used a file to make the tone hole, sanded it a little,
and added a mark so I could feel where to put my mouth. I can get some sound out, although it sounds pretty "pipey" (duh ).
Now I was wondering, are there any formulas or charts that say where I have to make the tone holes? I would also like to add an octave hole. Now it makes an "E", I'll check it later on with a tuner.
The brown stuff is some rust from the file...
Also: I'll probably have to remove the tape, so I can smooth out the the inside, although I don't know if it has such a large impact on the sound.

Greets.

Pictures:







The inside, my camera didn't know what the hell was going on


Update
Added the tone holes. I don't know, something seems wrong. It doesn't sound very great. I can barely get a full tone out of it and it seems like the tone holes are not far enough from eachother. Anyone got some tips on improving it? By the way, I added some rubber at the top for easy removal.