c#错误(使用接口方法):非静态字段、方法或属性需要对象引用

我在使用具有过时文档的第三方API时遇到了麻烦，所以我试图弄清楚为什么这段@#$!不是工作。@#$!我的意思是"代码"，当然:)

因此，据我所知，WAPISoap是我通过在visual studio中添加web引用而获得的公共接口。

我还知道description()方法接受两个参数，一个字符串和一个凭据类型的对象，它返回一个字符串。任何帮助都将是非常感激的:)

这是我到目前为止得到的:

using WAPIClient;
using System;
using Project1.WsWWDAPI;
namespace WAPIClient
{
    class ResellerAPI
    {
        public void CallDescribe()
        {
            String sReturnXml;
            Credential m_Crededential = new Project1.WsWWDAPI.Credential();
            m_Crededential.Account = "account";
            m_Crededential.Password = "password";
            String sCLTRID = System.Guid.NewGuid().ToString();
            sReturnXml = WAPISoap.Describe(sCLTRID, m_Crededential);
            Console.WriteLine(sReturnXml);
        }
        static void Main(string[] args)
        {
            ResellerAPI reseller = new ResellerAPI();
            reseller.CallDescribe();
        }
    }
}

WsWWDAPI.WAPI m_WAPIObj = null;
WsWWDAPI.Credential m_Crededential = null;
public void Init()
{
    m_WAPIObj = new WsWWDAPI.WAPI();
    m_Crededential = new WsWWDAPI.Credential();
    m_Crededential.Account  = "account";
    m_Crededential.Password = "password";
}
public void CallDescribe()
{
    String sReturnXml;
    String sCLTRID = System.Guid.NewGuid().ToString();
    sReturnXml = m_WAPIObj.Describe(sCLTRID, m_Crededential);
    Console.WriteLine( sReturnXml );
}
static void Main(string[] args)
{
    ResellerAPI reseller = new ResellerAPI();
    reseller.Init();
    reseller.CallDescribe();
}