How to design skin for dnn

a) design container
    <td colspan="4"><div runat="server" id="ContentPane"></div></td> because container should have a space for
   content of container,so "ContentPane" ought to be writen as above mentioned.

Reference links:
1.     D:\DRIVERS\develop\language\dotnet\portal\DotNetNuke\articals\blogs\全家福_chengulv\博客园 - 全家福 - DotNetNuke系列文 章-       Skin 與 Container 設計介紹.htm

Debug
    1.when custom design skin is wrong,to take it place with correct skin can fix problem.
   用好的SKIN文件覆盖掉自定的SKIN，就可使DNN恢复！！！！！！！！！！

    error info:
    1.The resource cannot be found
http://localhost/dnn31/Default.aspx?tabid=52&error=The+Controls+collection+cannot+be+modified+because+the+control+contains+code+blocks+
(i.e.+%3c%25+...+%25%3e).&content=0

answer to the error: A)There is a wrong with html file. There is no dnn token shown in design area in dreamweaver.
                               B)when upload the skin zip file,there is no signs of registration of control in ASP.NET custom control file