Open the picture, select the pen tool (shortcut key P), pay attention to the path mode, and draw a curve.

The method is to start from the vertex, hold down the mouse to drag the direction line (the tangent of the curve is downward), release it, and then go to the bottom point, and hold down the mouse to drag the direction line to control the path curvature. You can master it by doing a few more experiments. It doesn't matter if you draw it wrong. Press the DELETE key on the keyboard to delete it.

On the Layers panel, click the New button to create a new layer.

Select a brush and set the appropriate thickness. It is recommended to choose a brush with a hard edge. Then open the path panel, press Alt and click the stroke button. This step is very important. If you don't press ALT, the system will draw with a pencil, which is ugly.

Remember to select a brush for the tool, check the simulated pressure, and click OK.

At this time, the painting should be finished. If you think it is too thick or too thin, you can use CTLR+z or Ctrl+Alt+Z, and then press "["or "]" to control the thickness of the brush, and then click the strokes.

Go back to the Layers panel, select FX, and select the outer glow layer style.

The settings are as follows, and the colors are optional.

It's almost over.

If you want something special, such as hollowness, you can set the layer's fill to 0%.

You can keep asking questions.