Well its like a texture
Its like art for the flame
You can get a flame at market of at Items> Flames section
And its pretty hard to make a texture for it mostly i needs to be negativ but you need to just play around with it
first you need a flame that has been forged, then if you want to change the apperence of the particles or colour. thats what you use the particle texture for
Flames are typically more expensive the larger and colorful they are.
Probably because flames cause framerate issues to some users.
So better go pro before getting flames.