How to make the "glowing" effect on spark

You need a totally colored figure and a non-white background (otherwise the glow won't be that noticeable). But if you want to try it with white background, OK, fine. You should have something like this:



Select all the color layers:



And press Ctrl + E, this way you will merge all the colors into one single layer:



Make a duplicate of that layer by right clicking it and select the option "Duplicate layer". You will get a window like that, write down whatever name you want and click OK:



Drag the layer on top of the lines layer:



Change the blending mode to "Hard Light" as seen in the picture:



Go to Filter - Blur - Gaussian Blur. A window will pop out, choose whatever amount you want.



Et voilá!