Use a wizard to add a service reference for a C Sharp integration.

Go to the Solutions Explorer and select Service References > Add Service Reference. A wizard will appear asking for an address. Use: https://<instance name>.service-now.com/incident.do?WSDL. Accept the defaults for the rest of the wizard.

Open the app.config file and change the Security mode to "Transport" and the clientCredentialType and proxyCredentialType to "Basic"

Figure 1. Dot net app config