Calling a WCF web service

Hi folks.  I followed this documentation and things worked nicely.  https://docs.microsoft.com/en-us/dotnet/core/additional-tools/wcf-web-service-reference-guide

However, now I'm struggling to figure out how to send this SOAP service my credentials (un, pwd).

Here's what the Connected Service looks like...

https://photos.app.goo.gl/hA6ABN2DNVtXW5KC8

Can someone please help me invoke and send my credentials?  Then view the result?

Thank you!