Hey Gurus, 
I am trying to create a test class for a non-static method in a class. The class is as follows:

public class ServiceDeskCreateOpp
{

	public string oppRecordType { get; set; }
	public string oppName { get; set; }
	public date OppCloseDate { get; set; }
	public Id serviceDeskId;
	public Id OppAccountId;
	public List<account> SDAccount;
	//private final ServiceDesk__c serviceDesk;
	public ServiceDeskCreateOpp(ApexPages.StandardController stdController)
	{
		//this.serviceDesk = (ServiceDesk__c) stdController.getRecord();
		id serviceDeskId = apexpages.currentpage().getparameters().get('id');
		System.debug('serviceDeskId='+serviceDeskId);
		List<ServiceDesk__c> newServiceDesk = [select Client_Company_Name_Organization__c from ServiceDesk__c where Id = :serviceDeskId];
		if (newServiceDesk.size() > 0)
		{
			 OppAccountId = newServiceDesk[0].Client_Company_Name_Organization__c;
		}
		SDAccount = [select id, name from Account where id = :OppAccountId];
		if (SDAccount.size()>0 )
		{
			oppName = SDAccount[0].Name;
		}
		System.debug('OppAccountId='+OppAccountId);
		System.debug('newServiceDesk='+newServiceDesk);
		System.debug('oppName='+oppName);
	}

	Public PageReference OppCreate()
	{

		Opportunity op = new opportunity();


		op.Name = oppName;
		System.debug(oppName);
		op.z_Date_Last_non_USD_Hist_Rate_Check__c = System.today();
		op.StageName = 'Suspect';
		op.CloseDate = OppCloseDate;
		System.debug(OppCloseDate);
		System.debug(SDAccount[0].Id);
		op.AccountId = SDAccount[0].Id;
		op.recordTypeId = [SELECT Id, Name, SobjectType FROM RecordType WHERE SobjectType = 'Opportunity' AND Name = :oppRecordType].Id;
		op.Service_Desk_Requests__c = serviceDeskId;
		insert op;

		System.debug(System.Label.Opportunity_URL);
		PageReference pageRef = new PageReference(System.Label.Opportunity_URL + '?id=' + Op.id + '&sfdc.override=1');

		System.debug(pageRef);

		return pageRef;
	}

	public List<SelectOption> getSelectOpptyRecordType()
	{
		List<SelectOption> options = new List<SelectOption> ();

		options.add(new SelectOption('Client Renewal', 'Client Renewal'));
		options.add(new SelectOption('Default', 'Default'));
		options.add(new SelectOption('Partner Services', 'Partner Services'));
		options.add(new SelectOption('SMB', 'SMB'));
		options.add(new SelectOption('SMB Client Renewal', 'SMB Client Renewal'));
		options.add(new SelectOption('Sub-Contracted Services', 'Sub-Contracted Services'));
		options.add(new SelectOption('Technical Project', 'Technical Project'));

		return options;
	}
}

 and test class:

@isTest
private class ServiceDeskCreateOpp_Test  
{

@TestSetup
	static void setup()
	{

        Account testAccount = TestDataFactory_Account.Execute();
		insert testAccount;

		ServiceDesk__c testServiceDesk = TestDataFactory_ServiceDesk.Execute();
		testServiceDesk.Client_Company_Name_Organization__c= testAccount.id;
		insert testServiceDesk;
		
		Opportunity testOpporutnity = TestDataFactory_Opportunity.Execute();
		testOpporutnity.AccountId =testAccount.Id;
		insert testOpporutnity;

		system.debug('testing class:Account' + testAccount);
		system.debug('testing class:Service Desk' + testServiceDesk);
		system.debug('testing class:Opportunity' + testOpporutnity);

	}

	static testMethod void testServiceDeskCreateOppy()
	{
	  Account newAcc = [Select Id, Name from Account];
	  ServiceDesk__c newSD = [select id from ServiceDesk__c];
	  Opportunity newOpp = [select id,Name from Opportunity];

	  	PageReference pageRef = Page.ServiceDeskCreateOpp;
		Test.setCurrentPage(pageRef);
		ApexPages.currentPage().getParameters().put('id', newSD.id);

		ServiceDeskCreateOpp newSDOppty = new ServiceDeskCreateOpp();

        newSDOppty.OppCreate();

	  //ServiceDeskCreateOpp newOppty = new ServiceDeskCreateOpp();
	  //newOppty.OppCreate();
	  //OppCreate.OppCreate(newSD.id);
//	  ServiceDeskCreateOpp


	}
}

I am getting an error message that  "Error    1    Constructor not defined: [ServiceDeskCreateOpp].<Constructor>()    C:\Users\gagnihotri\Documents\The Welkin Suite\Projects\FullSand-New\FullSand-New\src\classes\ServiceDeskCreateOpp_Test.cls    36    1  "

Not sure what am I doing wrong