There is a shape in the form of a U around the LED footprint. Most LEDs should have a green marking on top. That side belongs on the side where the U shape is closed.

I have a collection of the common parts i buy regularly linked right here!

In the Bill of Materials (BOM) of the respective module you will find identifiers - for a potentiometer, for example, RV1. This identifier is also printed on the circuit board. This is where the respective component belongs.

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