How do I get the gender field to display on contact records?

I'm new to Salesforce NPSP, but I have figured out how to add a custom field. However, I can't seem to be able to figure out how to get an field that already exists in Salesforce to display. Specifically, I need to be able to see gender. Ideally, I'd like for there to be a picklist, but when I tried to create this, I got a message that this field already exists.  I'd appreciate any help you can send me.