That's what I hear about this place and why I decided to join, I lurked and found some genuinely pretty hateful threads though. Any advice on how to navigate this site for a noob?
Several people have replied to you already, but I want to throw in my two cents as well:
Don't assume that just because we all share a forum, that this place is a monoculture. This place isn't Reddit and you won't be banned for having the "wrong" opinion. People may disagree, but I never see (non-disruptive) disagreement result in a ban, no matter how unpopular the opinion in question is. There are many people from all sorts of different creeds all across the political spectrum that share this site, and reasonable minds both disagree and find common ground quite often in spite of general differences. Not only that, the place covering so many topics across so many boards means that not everyone is in every thread, and everyone casts a certain Venn Diagram over parts of the site relevant to them.
It might seem gauche at a glance to see threads that seem to be straightforwardly hateful, but something that countermands that in its own way is seeing a different hate thread in the exact opposite direction. Even more than that is seeing the people who frequent those opposite threads powing around and finding common sentiment (or at least coexisting, ignoring, and/or not antagonizing one another) in other unrelated threads. After all, most "hate" against a given demographic on this site in my experience tends to describe the general disposition of a group, rather than necessarily being absolute statements about every individual who shares the label, and I think most people here that would be described externally as -ists and bigots are, ironically, readily willing to make exceptions for exceptional people of those groups who break the stereotypes they dislike, or otherwise have positive qualities in spite of them.
Odds are good that if your opinion has at least some logical robustness, there'll be some folks who agree with it and want to talk about it, and something liberating about "anything is okay so long as it's not illegal" is that when people realize that no amount of rattling the cage will let them get rid of the people they disagree with, they learn to not fuck around in threads that have nothing to do with them.
In short, it's how a functioning society should work. We don't have to agree, but we do have to coexist, thus we gradually learn how to do it as frictionlessly as possible.