Adding New Pivot chart fields

[IkeWelsh]

Good Morning,

I am working with an excel file with a Pivot table in it.
I am wondering how to add a new Pivot Chart Field to my list of available fields (see image below)

I need to add some demographic fields like, Age, Duty Station, Office, Grade level,....

But I can't seem to find any information on how to add brand new chart fields, just how to include ones already in the list.

Thanks in advance for any assistance you can give on this.

Ike