How do I import multiple track files (GPX) into a single layer (in either Map or Earth)?

I want to have a map for each year, and for each map, I want a layer for each month. On the layer I want to have multiple tracks for my activities for that month on that layer in such a way that if I select the track, it will display only that track. I know it's possible to do, I just haven't been able to figure out how to do it on my own.

See this as a reference: https://www.google.com/maps/d/u/1/viewer?mid=1mtPYvvGvGfBaCohGXptseL9EitI&ll=36.64944933685908%2C-75.01781800000003&z=3