How to simulate a stock's time series?

Hi, Can anyone guide me on how to write a script to simulate a stock's time series?

I want to use a fat-tailed (leptokurtic)distribution with random sequences of High to Low volatility.

The script should also output ASCII data like this-

yyyy.mm.dd,HH:mm,Open,High,Low,Close

I also want to be able to set the return of 200-bar periods in 2 ways - manually and randomly.