Transmitting it to aliens ain't happening; we'd get them from radio to the present day, a couple hundred years' worth of technology, which is relatively little, and that's only if we manage to aim it right.

So, we want to communicate to future sapient species on Earth. I say take many, many plates of uranium glass and carve into it all of our most fundamental non-obvious knowledge: stuff like the periodic table, how to make electricity, how to make a microchip, some microchip designs, some software. And, of course, the scientific method, rationality, the non-exception convention (0 is a number, a square is a rectangle, the empty product is 1, . . .), and the function application motif (the way we construct mathematical expressions and natural-language phrases). Maybe tell them about Friendly AI, too.