Mate, here is a 'paint bar' you can apply to do it. Just paste that code into a new paint bar and then apply it to the chart. But there is a load of stuff on the forum and a load of walk through lessons you can take. It takes some time but so be it.

inputs:
 PriceH( High ),
 PriceL( Low ),
 PriceC( Close ),
 Length( 60 ),
 OverSold( 20 ),
 OverBought( 80 ),
 OverSColor( Cyan ),
 OverBColor( Blue ) ;

variables:
 MySlowK( 0 ) ;

MySlowK = SlowKCustom( PriceH, PriceL, PriceC, Length ) ;

if MySlowK Crosses Over OverSold then
 begin
 PlotPaintBar( High, Low, "SlowK", OverSColor ) ;
 Alert( "SlowK crosses oversold zone" ) ;
 end
else if MySlowK Crosses under OverBought then
 begin
 PlotPaintBar( High, Low, "SlowK", OverBColor ) ;
 Alert( "SlowK crosses overbought zone" ) ;
 end
else
 NoPlot( 1 ) ; { unpaint the bar }