Well you can't expect to start using the free lite version and become an instant expert on writing triggers - there is a bit of a learning curve to get through. The program is completely developed and will do almost anything you can think of.
1. You don't need any favourite above 3rd, because you can enter Card 6 or further in the selections box.
2. In your conditions use the following:
HiLo Last Card is in list A, 2
3. Add another trigger:
Back
Default Lay
All HiLo - Main Bets
First Matching Selection
Exactly in Round 3
Conditions:
Any selections matched lay is greater than 0
Also run it at first with the back trigger disabled, to see how many hits you get. I don't think that laying first will achieve much as the price of the selection will tend to drop as the game progresses.