how to add C# code in default.aspx in SharePoint

I am using SharePiont Server 2007 Enterprise with Windows Server 2008 Enterprise. I am developing using VSTS 2008 + C# + .Net 3.5. I want to add some C# code to default.aspx (more details, adding some logics to Page_Load method of default.aspx) and its code behind file. B开发者_如何学Cut I did not find default.aspx and its code behind file on disk? Where are they and how to modify?

BTW: another solution is to create a default.aspx file and its related code behind file by myself? But in this situation how to borrow the existing content/UI from current default.aspx (I am satisfied with current content/UI of default.aspx)?

I am not sure which solution is better and easier in my requirement to add C# code to Page_Load. Any advice or guides?

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What kind of functionality are you trying to add and is this a publishing page or part of a standard WSS site?

EDIT

Check out Andrew Connell's article on MSDN :-)

http://msdn.microsoft.com/en-us/library/bb986729.aspx

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Just a thought. How about creating a UI-less web part and adding it to the page ?