Lastly, take a look at the way of changing the lens.
When detaching, turn the lens counterclockwise till the red-colored dot on the lens coincides with the red-colored dot on the camera body, and then put the lens off of the camera body.
When attaching, do reverse as detaching. First coincide the red-colored dot on the lens with the one on the camera body, and then turn it clockwise till it stops.