You start by asking for a circuit diagram, i.e. hardware.

Then you say that you can't figure out what needs to be added to the code, i.e. software.

Then you return back to hardware again, by mentioning blown chips.

The example does not need any extra components but the processor and the crystal. Any circuit diagram you can find with your processor and a crystal should be enough. Just as always, you have to think about a proper reset solution, capacitors for the power supply, capacitors for the crystal etc.

Then it is up to you to combine this code with your own code, since it is meaningless to have a software-based RTC unless you have some code that makes use of it - for example by displaying the time on a display, or filtering digital inputs depending of time-of-day.