Open the control panel on the upper right.
Click Viewpoint and "Allow change" to enable moving around, then left click and drag to change viewing angle.
Right click and drag to change viewing position.
Center click or scroll to change viewing distance.
Change the vector with its control menu.
A vector in three dimensions is described by its components on the x, y and z axes.
Here X is red, Y is green, and Z (out of the screen) is blue.
A vector is also described by its length, and the angles θ and φ.
θ is measured "down" from the +z-axis increasing toward the -z direction. It is 90° in the xy-plane.
φ is measured in the xy-plane from the +x-axis with the angle increasing toward the +y-axis.