how do I find Default gateway on my home network

Generally you'll have several interfaces showing...

After highlighting Wifi above & clicking the advanced button, then TCP/IP tab you see...

If I select an interface that isn'r connected I get no Router/Default Gateway...

DEpends what version of OSX, but in System Preferences>Network>TCP/IP it'll be called Router on the Mac.

Hmm.. followng these instructions but there is nothing listed under Router.

Back ti researching...

Which version of OS X are you using?

Did you highlight the Interface before looking for TCP/IP tab?

Hey - what did you mean by "highlight the interface"?
Thank you.