Good ol' Herr Fraunhofer. The institute that bears his name has been one of my best customers for years.
Literally that easy. You literally just point the dish at Earth. The built-in high-gain antennas on the LM and CSM were aimed by the computer, so the astronaut had to do nothing more than tell the computer, "Point the dish at Earth now, please." The LRV and erectable S-band antennas were literally aimed by hand, just by pointing the dish at the prominent blue thing in the sky. In the J-missions they did this by hand every time the LRV stopped.
And no, the prominent blue thing in the sky wasn't whizzing around at breakneck speed as in the AI slop video. It stays in the same place in the sky for days on end, moving in a tight figure eight. And it spins slowly enough that you have line-of-sight to a point on Earth's equator for up to 12 hours a day. Because Earth's orbit is tilted with respect to Earth's rotational axis, some high-latitude receivers can maintain continuous contact for a week or more.