Creating Puzzles - Training.

[Rapture]

You might as well be asking someone how they create great music, or a great piece of art. Just do it, start off wherever you feel like it and build it up like how everyone else does it.

Give yourself a basic task like I want someone to click a button to open a door to the end, then add a jumping mechanic to it, then add another thing, then another, then another and so on.