I recommend you keep the incense stick out of the shot. Be very careful to keep light off the background.
You can crop the photos. Make the photo a negative to change the background to white, which is why you take care to keep light off the background. I us e afelt material because it really absorbs any stray light.
Here is yours cropped, rotated, and made a negative. As you can see your background was not completely black, because the background in the negative has some color to it;
It looks like the shift key on your keyboard is only working part of the time.
Copy the background layer, or make a new blank transparent layer, and set the blending mode to 'Color'. Select a soft edged brush of the appropriate size, and a foreground color you want to use. Apply the color where you want it with the brush.
Again, a black background is very important, kind of like making the appropriate capital letters when you type a post, or the brush strokes will show on both the background and the smoke, making a half-assed looking piece of work.