Given an example:
7 Million shares / 9 Million orders = 0.777
I have 50,000 share order @ 0.001, total 50 btc
50,000 x 0.777 = 38,850 shares
My share become 38,850 and it's worth 0.001287 per share
The higher number of orders the higher the price per share will be.
You will 'buy' 38,850 shares @ .001. for a total of 38.85 btc. The remaining 11.15 btc will still be in your balance at btct.co.