dotnet DLL

i have a applicatoin where the code behind is made in DLLS now i want to update the code since i have the components (source code) i changed the required code but the default DLL r being fired insted of taknig my changed code page ..

1) how can i make my application to use my source code files Or
2)how cani change the DLL to be placed my new DLL

The DLL is the compiled version. You can delete it and let the server recompile if the settings don't have the check in place to recompile on change.