Can someone give me a good explanation how to change the effects on blizzard

I winder how i must do to make a spell like blizzard and make green
ice balls fall from the skies instead of those ice balls.

Find the path of the ice-ball textures out and recolor them with a painting tool, import them into your map with the same path - it's as easy as that

you might have to channel out the original ice shards and create your own green balls in photoshop or something.

I have tried to make the file frost3test.blp green and replaced it again but it wont work when i cast blizzard.

import it with programs found in the download section.

When i have imported it to the editor i can only use it as an icon not as an effect or a buff.
So how do i fix that