Fox News has never, from its earliest inception, been anything except explicit right wing propaganda. It’s a shame that anyone dirties their brain by watching it.

A Rolling Stone article about Fox News’s rise from 2011 is still the most complete and methodical explanation for how it started:

First, they bought an audience:

In the normal course of business, cable outfits like Time Warner pay content providers like CNN or MTV for the right to air their programs. But Murdoch turned the business model on its head. He didn’t just give Fox News away – he paid the cable companies to air it. To get Fox News into 25 million homes, Murdoch paid cable companies as much as $20 a subscriber. “Murdoch’s offer shocked the industry,” writes biographer Neil Chenoweth. “He was prepared to shell out half a billion dollars just to buy a news voice.” Even before it took to the air, Fox News was guaranteed access to a mass audience, bought and paid for. Ailes hailed Murdoch’s “nerve,” adding, “This is capitalism and one of the things that made this country great.”

Then they filtered every person in the organization to ensure right-wing bias:

Ailes then embarked on a purge of existing staffers at Fox News. “There was a litmus test,” recalled Joe Peyronnin, whom Ailes displaced as head of the network. “He was going to figure out who was liberal or conservative when he came in, and try to get rid of the liberals.” […] If staffers had worked at one of the major news networks, Ailes would force them to defend working at a place like CBS – which he spat out as “the Communist Broadcast System.” To replace the veterans he fired, Ailes brought in droves of inexperienced up-and-comers – enabling him to weave his own political biases into the network’s DNA. To oversee the young newsroom, he recruited John Moody, a conservative veteran of Time. […] the Chairman gave Moody explicit ideological marching orders. “One of the problems we have to work on here together when we start this network is that most journalists are liberals,” Ailes told Moody. “And we’ve got to fight that.” Reporters understood that a right-wing bias was hard-wired into what they did from the start.

And starting 2000, they were directly putting their finger on altering the outcome of elections:

But it was the election of George W. Bush in 2000 that revealed the true power of Fox News as a political machine. According to a study of voting patterns by the University of California, Fox News shifted roughly 200,000 ballots to Bush in areas where voters had access to the network. But Ailes, ever the political operative, didn’t leave the outcome to anything as dicey as the popular vote. The man he tapped to head the network’s “decision desk” on election night – the consultant responsible for calling states for either Gore or Bush – was none other than John Prescott Ellis, Bush’s first cousin. […] On Election Day, Ellis was in constant contact with Bush himself. After midnight, when a wave of late numbers showed Bush with a narrow lead, Ellis jumped on the data to declare Bush the winner – even though Florida was still rated too close to call by the vote-tracking consortium used by all the networks. Hume announced Fox’s call for Bush at 2:16 a.m. – a move that spurred every other network to follow suit, and led to bush wins headlines in the morning papers. […] “We’ll never know whether Bush won the election in Florida or not,” says Dan Rather, who was anchoring the election coverage for CBS that night. “But when you reach these kinds of situations, the ability to control the narrative becomes critical. Led by Fox, the narrative began to be that Bush had won the election.”

Since then, it’s gotten many orders of magnitude worse of course. But as they shift the Overton window rightward, their propaganda also becomes “normal,” and barely worth reporting (which accelerates the shift further, and so on).