How to make a SOAP/WSDL client in C#?

You can use the WSDL tool to generate a C# file which will contain the necessary types and members to talk to the web service or you could add a Web Service reference. See here for more details.

The simplest way is to use VS and add a web reference. This automatically creates the stub for you

If your preferred approach is to control the generated code, it's best to use the more recent SvcUtil.exe in place of Wsdl.exe.

See also WCF proxy generation: svcutil.exe vs wsdl.exe