Arduino IDE ATMega324A

Hi everyone, I have a problem with atmega324a, I would like to import it into the IDE Arduino (Win) online but can not find a useful guide for setting up the ide
can anyone help me out? (I do not care the booatloader, I have a MK2 AVRISP)
Thank you

Perhaps this.

You generally need a core (see above).
Minimally, you need a variant and an entry in boards.txt.

Yup - The MCUDude MightyCore supports the 164/324/644/1284. That's all you need. I think it's even got optiboot.