The stem-like half of the snap is called the stud. The flat metal surface on this part makes it ideal for soldering to a flat pad on a circuit board. Align one stud to the pad you just tinned, and heat the post through until the pad's solder becomes molten again.

While the solder is molten, apply another small amount of solder. It should stick to the stud and wick into/around one or more of its needle holes.

You may need to shift the stud around with your soldering iron to get it into position before allowing the joint to cool. Now the solder is mechanically connecting the stud to the board as well as electrically connecting the corresponding pin on the Flora.

Some discoloration may occur as the snap's tin plating shifts with the application of heat and solder. It may reveal its brassy core!