Server side code is found in the code behind file (you can output a string of code that will get printed on client browser like java script etc which will get executed on client browser but only line of code that can get executed ofn server is included in code behind file)
Server side code is found in code-behind class.Since code-Behind is executed on the server.
How to create a DB connection at one place/page so that we can use that connection for all pages/forms/windows.what r the steps ned to be performed. if question not clear,let me know.