Installing Vinyl Patio Door

Got a Home Depot Vinyl Patio Door with fins. 2 Questions.

1) There is a sticker on the top fin that says "Do not nail head". What does this mean??? Don't nail the top fin?


2) I have seen people use a product like the sticky stuff used on roofs for ice damming around the door openings. Now they apparently sell a specific product for doors and windows. On the label it has installation going flat on the edge of the opening. I have seen people install this item , but folding it overthe opening. Bottom first, then sides then top. What is the proper way to install this product and should the top piece go on top or under the top fin?

Thanks

 

I assume that it means do not nail up through the door frame header. You nail the fin only.
All flashing, whatever the type of material, goes up under the uppermost layer. Put it over the fin.
Mike