If you want the source then you need to download the source code - it is available as well.

But, really not needed - you can still modify allot just by using the install package (not recommended though).

There are plenty of "how to install dotnetnuke" video tutorials out there on the web.

You usually download and install INSTALL package, even for module and skin development.
If necessary, you may install symbol files as well to access DNN internal code during debugging.
You should stay away from modifying code of the core framework, unless you know, what you are doing - otherwise, you might get issues upgrading (and your changes will be overwritten).

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Cheers from Germany,
Sebastian Leupold

   

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