WARBALLS- help on displaying postprocess effects

I need help on displaying a sharpen effect on a player when it gets hit by a ball for about 1s…what i don’t know is how to do it. What function should i use to display the effect? Or, if its to tricky, to display an overlay on him.

code using pl as player.

pl:doShit( )

Thanks for reading until down here.
And here.