This is actually quite simple.

Make sure you get all your arrow info and the setup measurements in the program where needed. If you have your chrono speed it will give a little better peace of mind, but it's not absolutely necessary. I think it needs peep to pin measurement, peep to center of arrow, DL, maybe some others.

1) Go sight in at whatever 2 distances you like. I do 20 and 50 or 60. You did 20 and 80, even better. Make sure they are perfect as you can get them.
2) In the sight configuration tab there is a choice of "inch", select this and put in the 2 measurements it asks for. I have measured both on my draw board and had my wife measure while at full draw. Both worked fine, drawboard was way more comforting and trustworthy.
3) Now the "Sight In" tab. For "range 1" input 20 yards. For "Mark 1" simply input "1" regardless of what it actually is on your sight. Forget those numbers if there are any, they mean nothing here.
4) Now measure the distance between your 20 and 80 marks you got when sighting in.
5) Convert this measurement to a decimal and add it to the 1.
6) For example: Say the distance is .500 between 20 and 80. Range 1 would be 20 and mark 1 would be 1. Range 2 would be 80 and mark 2 would be 1.500.
7) Hit the calculate speed button and it should be within a foot.
8) Print the tapes and find the one that matches your marks.
Go test her out.

It is very important to get the measurement between your marks as EXACT as you can.

I hope this helps. Good luck.

 

Use the very first option on the sight menu, no special calibrations needed