My iMac wont let me activate the Airport setting

I have an old iMac 10.4.11.

It's really old and I need to update it, but first I'd like to change it to the Airport setting.

It is currently on the built-in Ethernet setting, but it does now have the Airport setting.

I'd like to know if it is possible to change it to th Airport setting in some way?

Thanks in advance! 🙂