C#如何通过用户输入用浮点值模块化地填充列表，计算总和和平均值

请注意，我有C++背景，我的导师应该被称为MOST的作业监督者。没有任何指示或指导。现在，有没有可能有好心人能帮助我，帮我找出我做错了什么，然后解释（用杜尔杜尔语言）如何修复它，使其编译？？？这是代码和错误。从22点开始，但最后9点要了我的命，现在是凌晨3点。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace P1_Wilson
{
 class P1_Wilson
  {
    float sum;
    float aver;
    int counter;
    static float FillNumber()//Declaration of method utilized to fill an array/list of                              floating point numbers.
     {
       int counter = 0;
       List<float> floatlist = new List<float>();
       char sentinel;
       Console.WriteLine("I would like you to now input a few floating point numbers.'n                           Enter q to quit.");
       Console.WriteLine("You have the option to quit now.'nWould you like to continue? 'nEnter q to quit.");
       sentinel = char.Parse(Console.ReadLine());
        while (sentinel != 'q')
         {
          Console.WriteLine("You have the option to quit now.'nWould you like to  continue?'nEnter q to quit.");
          sentinel = char.Parse(Console.ReadLine());
          Console.WriteLine("Then please input a floating point number.");
          floatlist[counter] = float.Parse(Console.ReadLine(floatlist[counter]));
          counter++;
          return floatlist;
          return counter;
         }
     }
    static float CalcSum(List<float> floatlist, int counter)//Declaration of method  used to add all entered numbers together and calculate the total sum.
     {
      for (; counter >= 0; counter--)
       {
        float sum = sum + floatlist[counter];
       }
       return sum; 
     }
    static float CalcAver(float sum, float aver, int counter)//Declaration of method used to calculate the average of numbers entered.
     {
      aver = sum / counter;
      return aver;
     }
    static void Main()//Where execution of program begins. Introduces user to program. Prompts for user input and calls all subservient methods.
     {
      FillNumber();
      CalcSum();
      CalcAver();
      Console.WriteLine("The total number of floating point numbers entered is:" +  counter); 
      Console.WriteLine("The total sum is:" + sum);
      Console.WriteLine("The average of the numbers entered is:" + aver);
      Console.ReadLine();
     }
  }
}

这些是我的错误：9

错误1方法"ReadLine"的无重载需要1个参数错误5方法"CalcSum"的重载不包含0个参数错误6方法"CalcAver"的重载不包含0个参数错误2无法将类型"System.Collections.Generic.List"隐式转换为"float"错误3非静态字段、方法或属性"P1_Wilson.P_Wilson.sum"需要对象引用错误8非静态字段、方法或属性"P1_Wilson.P_Wilson.sum"需要对象引用错误7非静态字段、方法或属性"P1_Wilson.P_Wilson.counter"需要对象引用错误9非静态字段、方法或属性"P1_Wilson.P_Wilson.aver"需要对象引用错误4"sum"与声明"P1_Wilson.P1_ilson.sum"冲突

如果我的一次拙劣的幽默尝试更多地引起了愤怒，而不是善意地引起笑声，我深表歉意。