Missing "L" and "R" Buttons on Circuit Boards

I've recently gotten two switches to try to fix for fun, and discovered that one is completely missing the internal button on the daughter-board that the "L" trigger is meant to push, and both are missing the one on the mother-boards for the "R" trigger.

I've already found replacement buttons online, and assume I'll have to solder them. I have some experience soldering, in that I own and know how to use a soldering iron, but have never actually used it on electronics.

Are there any existing tutorials online of how to do this? I'd like to try doing it myself, once, just for the sake of learning, and then if it doesn't work out I'll probably just buy new, completely intact boards.

Any resources or advice would be greatly appreciated.

(Images are of one complete board with the button attached, and one broken board with the button missing, for comparison.)