How to use Gann Calculator for Short term and Long term trading?

Hello,

I wanted to know how to construct and use Gann Calculator for :
1. Short term trading - (1-3 weeks)
2. Long term trading - (1-6 months)
3. Price Reversal dates - i believe Gann had come up with something that can give future dates on which major price reversals are expected.

Any pointers to the above topics?

Thanks!