I created an apex class and I downloaded the wsdl for that class. I also have downloaded the wsdl for the sandbox. I try to access this class in c# and I am getting an invalid login session error. I am guessing this is beause I am loging into the sandbox instead of the webservice class, but I dont see that I can login using the webservice class?? Is there a way to add loggin ability to the webservice class? Does this make sense?

So basically I dont really need to login into the sandbox, I just need to login into this webservice class I created in the sandbox but there doesnt seem to be a way?

Thanks 

Apex class 

global class CorePattern
{
    
        WebService static string GetPattern(string penSerNbr, string shelfSize)
        {
            return '';
        }

 System.Web.Services.Protocols.SoapException: System.Web.Services.Protocols.SoapHeaderException: INVALID_SESSION_ID: Invalid Session ID found in SessionHeader: Illegal Session
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)