Hi
As a newbie I'm trying to learn to use methods... and I'm a bit stuck 
. This is what I'm trying to achieve [I'm expanding an exercise from the internet]:
1. select one of 3 countries from a comboBox [cboCountry] - show selected country in cboCountry
2. enter amount of cash to do calculation on [txtAmount]
3. depending on which country is selected will depend on the FxRate - which will show in the textBox txtFxRate
4. txtSubTotal (taxableAmount) should show figure entered in txtAmount * figure entered in txtFxRate [as passed by the cboCountry]
5. txtCashierFee should show 2% on the subTotal [cashierFee of 2% on the taxableAmount]
6. txtGrandTotal then shows subTotal + cashierFee
These are the two errors I get:
C:\BEGIN2\code\Lesson4x\ForEx\Form1.cs(265): 'displayResult' denotes a 'variable' where a 'method' was expected
C:\BEGIN2\code\Lesson4x\ForEx\Form1.cs(236): The name 'fxRate' does not exist in the class or namespace 'ForEx.Form1'
Many thanks for your help in advance 
My code:
private void btnDollar_Click(object sender, System.EventArgs e)
{
#region select
switch(cboCountry.Text)
{
case "USA":
{
fxRate = 1.74743;
break;
}
case "PHIL":
{
fxRate = 89.4507;
break;
}
case "SAU":
{
fxRate = 6.55381;
break;
}
}
#endregion
double fxRate;
double taxableAmount; //subtotal
double cashierFee; // 2%
double grandTotal;
double displayResult;
txtFxRate.Text = cboCountry.Text.ToString();
txtTaxableAmount.Text = taxableAmount.ToString();
taxableAmount = calculateTaxableAmount(taxableAmount, fxRate);
cashierFee = calculateCashierFee(taxableAmount);
grandTotal = calculateGrandTotal(taxableAmount, cashierFee);
displayResult = displayResult(grandTotal);
}
#region private methods
private double calculateTaxableAmount(double taxableAmount, double fxRate)
{
return taxableAmount * fxRate;
}
private double calculateCashierFee(double taxableAmount)
{
return taxableAmount * 0.02;
}
private double calculateGrandTotal( double taxableAmount, double cashierFee)
{
return taxableAmount + cashierFee;
}
private void displayResult(double grandTotal)
{
MessageBox.Show("grand total = " + String.Format("0.C)", grandTotal));
}
#endregion