从网上找了一个注册的代码，有点看不懂。有没有人帮忙解释一下
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Security.Cryptography;


public partial class userreg : System.Web.UI.Page
{
    public string fname;


    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            xingbie.Items.Add("男");
            xingbie.Items.Add("女");

            xueli.Items.Add("高中");
            xueli.Items.Add("大专");
            xueli.Items.Add("本科");
            xueli.Items.Add("硕士");
            xueli.Items.Add("博士");

            jisuanjishuiping.Items.Add("一级");
            jisuanjishuiping.Items.Add("二级");
            jisuanjishuiping.Items.Add("三级");
            jisuanjishuiping.Items.Add("程序员级");
            jisuanjishuiping.Items.Add("工程师级");

            yingyudengji.Items.Add("三级");
            yingyudengji.Items.Add("四级");
            yingyudengji.Items.Add("六级");
            yingyudengji.Items.Add("八级");
            //addxiala("kehuxinxi", "bianhao", "kehubianhao");
        }
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        string a=IMGCODE1.Text.Trim();
        string b = TextBox1.Text.Trim();

        if (a.Equals(b, StringComparison.OrdinalIgnoreCase))              这个if语句和框里语句是什么意思呢
        {
            string sql;
            if (UploadFile.Value != null && UploadFile.Value != "")
            {
                hsgupload();