How to consuming webservice having WSDL and XSD files?

Question

Hi sir,

We've requested a company to write a webservice that we can use to get some information.They have sent us WSDL and XSD files. Could you please tell me how I can use these files to query data? I can do it easily if I have a link to a webservice. I just provide the link and Visual Studio generates web reference for me. After that I can use that reference just like a normal class. In this case I have no link. Just above mentioned files.

I cant able to pass the parameters into the method defined in wsdl file, it shows object reference not set to an instance of the object.
Can anyone tell me how to use xsd file to pass the parameters into wsdl webservice method to get the response from the webservice.
Kindly give me the solution for this problem.