Hi Andrew, there are a few different ways you could draw an arc like you're describing. One way is to make a circle first and then cut pieces of it away using the Edit > Trim command with the "Add trim points" option.

Or also if you draw a circle where you want if you then draw an arc using Draw curve > Arc > Center and snap the center point onto the circle's center it should draw in the circle's plane and then you could delete the circle.

Another way is to use View > Cplane to set the construction plane and then that sets the default plane that commands like arc will draw on.

Or also you could draw it flat initially and use Transform > Rotate > Axis to rotate it up to vertical.

Let me know if you need more information on any of these methods.

- Michael