I need help with my C# Homework ? What did I do wrong.

You've got a few problems there, but nothing too serious :)

Try it like this:

using System;
using SC = System.Console;
public class JKingLab04
{ // Main Method
    public static void Main()
    {
        Double hoursWorked, payRate;
        Double grossPay, stateTax, federalTax = 0, dblFICA = 0,
        netPay = 0;
        string hoursWorkedStr, payRateStr; 

        SC.WriteLine("Lab 4 – Jenni King");
        SC.Write("\nPlease input hours worked: ");
        hoursWorkedStr = SC.ReadLine();
        SC.Write("\nPlease input rate of pay: ");
        payRateStr = SC.ReadLine();
        hoursWorked = Convert.ToDouble(hoursWorkedStr);
        payRate = Convert.ToDouble(payRateStr);

        grossPay = CalcGrossPay(hoursWorked, payRate);
        CalcStateTax(out stateTax, grossPay);
        CalcFedTax(ref federalTax, grossPay);
        CalcFICATax(ref dblFICA, grossPay);
        CalcNetPay(ref netPay, grossPay, stateTax, federalTax, dblFICA);

        SC.WriteLine("grossPay ({0}) = hoursWorked ({1}) * payRate ({2})", grossPay, hoursWorked, payRate);
        SC.WriteLine("netPay ({0}) = grossPay ({1}) - state tax ({2}) - federal tax ({3}) - FICA ({4})", netPay, grossPay, stateTax, federalTax, dblFICA);  
        Console.ReadLine();
    }

    public static double CalcGrossPay(double hours, double rate)
    {
        double gross;
        gross = hours * rate;
        return gross;
    }
   
 
    public static void CalcStateTax(out double stateTax, double grossPay)
    {
        stateTax = grossPay * 0.04;
    }

    public static void CalcFedTax(ref double federalTax, double grossPay)
    {
         federalTax = grossPay * 0.23;
    }

    public static void CalcFICATax(ref double fica, double grossPay)
    {
         fica = grossPay * 0.14;
    }

    public static void CalcNetPay(ref double netPay, double grossPay,
         double stateTax, double federalTax, double dblFICA)
    {
         netPay = grossPay - stateTax - federalTax - dblFICA;         
    }
}