How to use code to give discount?

Hi


I am trying to write a dicount module in AX.

how can i add discount percent or discount amt to line via code?

because i can't direct assign value to discAmount field.
any suggestion can give me?

    SalesTable ss;

    DialogButton diagBut;

    str strMessage;

    str strTitle;

    SalesLine newsalesLine;

    SalesLineDiscount newsLineDiscount; 

    ;

    super();

    strMessage = SalesTable.SalesId; //"The No button should have initial focus.";

    strTitle = "Title";

    diagBut = Box::yesNoCancel(

        strMessage,

        DialogButton::No, // Initial focus is on the No button.

        strTitle);

    newsalesLine.clear();

    newsalesLine.SalesId =  SalesTable.SalesId;

    newsalesLine.ItemId = "TEST02";

    newsalesLine.QtyOrdered = 10;

    newsalesLine.PriceUnit = 20; 

   //newsalesLine.discAmount  = 10;

    newsalesLine.createLine(NoYes::Yes, // Validate 

    NoYes::Yes, // initFromSalesTable 

    NoYes::Yes, // initFromInventTable  

    NoYes::Yes, // calcInventQty 

    NoYes::Yes, // searchMarkup 

    NoYes::Yes); // searchPrice 

    SalesLine_ds.research(true); 

    SalesLine_ds.refresh();