I need to help for writing Buy & Sell

I can not write buy and sell condition! can you help me?



_SECTION_BEGIN("R.P");
_N( TickerList = ParamStr("Tickers", "^DJI,MSFT,GE") );
NumBars = 20;
fvb = Status("firstvisiblebar");
Plot( 100 * ( C - C[ fvb ] ) / C[ fvb ], Name(), colorBlue );
for( i = 0; ( symbol = StrExtract( TickerList, i ) ) != ""; i++ )
{
fc = Foreign( symbol, "C" );

if( ! IsNull( fc[ 0 ] ) )
{
Plot( 100 * ( fc - fc[ fvb ] )/ fc[ fvb ],
symbol,
colorLightOrange + ( (2*i) % 15 ),
styleLine );
}
}
PlotGrid( 0, colorYellow );
_N( Title = "{{NAME}} - Relative Performance [%]: {{VALUES}}" );
_SECTION_END();

this AFL is for relarive performance and not for buy-sell decision.