Help with a roundabout (pics)

Okay so, from your starting point, both the left and the right lane can go straight, so it makes sense that you were honked at for trying to go left from the right lane. If a car to your left was going straight while you're going left, that could cause an accident. So yeah, don't do that.

I found this helpful image from New Hampshire's Department of Transportation
https://gamefaqs.gamespot.com/a/user_image/1/0/2/AAQgjdAAEiEG.jpg