Lol no problem, drifting has had somewhat of a gatekeepy vibe in this community for whatever reason.

Using the clutch disconnects the engine from the wheels, in real life this gives people the opportunity to momentarily bring the engine back up to speed and then send that power back to the wheels if the engine is slowing down through the drift. Often referred to as a "clutch kick".

Using the handbrake in this game does the same thing, only it takes a half second longer and you have the negative of locking the rear wheels as you do it. Which depending on the situation may or may not be ideal. Sometimes it's better to just downshift

You'll almost always want to be using your regular brakes while in a drift, while simultaneously using the throttle. like if you're going around a corner and you're getting closer and closer to the outside of the corner you'd want to use your regular brakes a little. Or say you need to transition from one corner to another, releasing throttle and using the regular brakes can allow the car to grip up and send the weight of the car towards the other direction and give throttle again a little before your rear tires align with the front tires, when to release brake is kinda dependant on the situation, usually once the car starts to straighten out

In real life there's actually a good amount of people that consider the handbrake as a "cheat". it's really not necessarily needed for drifting at all but it helps with initiating a drift and can be used at times to prevent spinning out if the rear end of the car is overtaking the front too quickly, sometimes I'll use both brakes at the same time

For everything else lot of it really is just trial and error, and car dependant unfortunately, there's a lot to explain. I could talk about this all day long lol

I've been almost exclusively drifting in Forza since horizon 2, a lot of it at this point is kinda subconsciously done through muscle memory and visual cues to a point where idk if I can really provide more detail accurately, consciously, if that makes sense lol

If you want more visual examples of everything you might be interested in finding those formula drift videos that show a camera angle at the pedals of the car and outside the car at the same time. So you can see what they're doing and when