How to create a neon light effect

[rich2005]

There is no one way for this type of image.

You might select a foreground, add a background. Desaturate those (make shades of gray).

Add a gradient in a suitable mode.

Then all the text and other little embellishments are added separately.

The only real way is experiment with Gimp and gain experience using it.
quick example: https://i.imgur.com/wVAyCZw.jpg