How do you obtain gold?

By mining it from the earth.

Gold is found in ores made up of rock with very small or microscopic particles of gold. This gold ore is often found together with quartz or sulfide minerals, these are called "lode" deposits. Native gold is also found in the form of free flakes, grains or larger nuggets that have been eroded from rocks and end up in alluvial deposits (called placer deposits). Such free gold is always richer at the surface of gold-bearing veins owing to the oxidation of accompanying minerals followed by weathering, and washing of the dust into streams and rivers, where it collects and can be welded by water action to form nuggets.

Gold extraction from ore grades as little as 0.5 g/1000 kg (0.5 parts per million, ppm) can be economical. Typical ore grades in open-pit mines are 1-5 g/1000 kg (1-5 ppm); ore grades in underground or hard rock mines are usually at least 3 g/1000 kg (3 ppm). Because ore grades of 30 g/1000 kg (30 ppm) are usually needed before gold is visible to the naked eye, in most gold mines the gold is invisible.

In all of history, only 161,000 tons of gold have been mined, barely enough to fill two Olympic-size Swimming Pools.