辞职申请理由:刷一次变一次图的ASP代码，我看不明白

下面是代码，但是我根本看不明白，里面到底要改哪几样，改好的文件叫什么名字？？？？？？
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刷一次变一次图的ASP代码

<%@LANGUAGE="VBSCRIPT" CODEPAGE="936"%>
<%
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转发时请保留松?餍畔?这段声明不并会影响你的显示速度!
************************* 随机图片显示 ****************************
使用实例:img.asp?list=图片存放目录
使用注意:图片目录放于本文件同目录下!需要FSO支持!
说明：只要将变化图片放于一个目录下，修改下面程序的（需要修改的地方）成你的目录名称！
上传本程序和图片文件夹到同一目录下，在发帖时候使用UBB代码形如：即可！
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Function AllPath()
Dim Domain,GFilePath
Domain = Request.ServerVariables("SERVER_NAME")
GFilePath = Request.ServerVariables("PATH_INFO")
GFilePath = lcase(left(GFilePath,instrRev(GFilePath,"/")))
AllPath = "http://";&Domain&GFilePath
End Function

Function ShowFileList(folderspec)
Dim Path,objFSO,objFolder,count,objFile,nume,S
Path = Server.MapPath(folderspec)
Set objFSO = Server.CreateObject("Scripting.FileSystemObject")
If objFSO.FolderExists(Path) Then
Set objFolder = objFSO.GetFolder(Path)
count = 0
For Each objFile in objFolder.Files
count = count+1
Next
randomize
nume = Int((count*rnd)+1)
S = 0
ShowFileList = ""
For Each objFile in objFolder.Files
S = S + 1
If S = nume Then
ShowFileList = objFile.Name
Exit For
End If
Next
Set objFolder = Nothing
Else
ShowFileList = "NO"
End If
Set objFSO = Nothing
End Function

Dim list,filename,address,str

list = trim(Request.QueryString("list"))
if list = "" then
Response.write "本页需要正确参数引入,您缺少相关的参数！正确格式如下："&AllPath&"img.asp?list=（需要修改的地方）"
Response.End()
end if

filename = ShowFileList("./"&list&"/")
if filename = "NO" then
Response.write "您指定的目录<b>"&list&"</b>不存在，请重新指定！"
Response.End()
end if

if filename = "" then
Response.write "您指定的目录<b>"&list&"</b>没有相关的图片文件存在，请重新指定！"
Response.End()
end if

str = right(filename,3)
if str<>"jpg" and str<>"gif" then
filename = "erro.gif"
end if

address = AllPath&list&"/"
address = address&filename
%>
<%Response.redirect(address)%>