First things first. Download and install the FreelancerSDKv1.3.
The SDK is the only way (for noobs anyways
) to get the ini files.
When you install it, it will ask you where to install it. Install it to your Freelancer base folder. I.E. C:\Program Files\Microsoft Games\Freelancer
Then all the ini files and such will be install there. Then you go to that folder and open the files and start poking around. The ones you want are the obvious ones. Just look for entries with "price = " in it and change it to whatever you want.
Now, go do some research as I think the search button in the forums is broken. Other than that, download Dritzz's Complete ship creation guide version 4 and in there are some instructions on changing price and engine speeds, and shield strength and hull strength and cargo.
Good luck.