Java HotSpot Virtual Machine

First, I realize that this is a JNI forum, but I am having a hard time finding a JNA forum.
I was hoping that someone here would be familiar enough with JNA to answer my question.
If not, then maybe I can use JNI to perform the tasks I need.
I know vitrually nothing about JNI or JNA, but it looked that JNA might be a bit less complicated to learn.

I have a c++ dll that contains a class named CJNA_Test(void)
This class contains two functions SetCallbacks and TestCallbacks

I understand how to access functions from inside a dll - here is an example of my java class that sets up the function definitions.

package jnatest3;

import com.sun.jna.Native;
import com.sun.jna.Structure;
import com.sun.jna.win32.StdCallLibrary;

public interface IrisCapture extends StdCallLibrary {

        public IrisCapture INSTANCE=(IrisCapture)Native.loadLibrary("IrisCapture",IrisCapture.class);    
        public void ICaptureInit();
        public int ICaptureClose();
        public int ICaptureOpen(String strAddress, String strSerial);
        public int ICaptureStartIrisCapture( int purpose, int whichEye, int fedLevel, int timeout, int auditFace );
        public int ICaptureStopIrisCapture();

}

And here is my test application

public class Main {

    public static void main(String[] args) {
        System.setProperty("jna.library.path","D:\\NetBeansProjects\\");
        String s = System.getProperty("jna.library.path");
        System.out.println( "Jna.library.path = "+s );
        IrisCapture ic = IrisCapture.INSTANCE;
        System.out.println( "IrisCapture: "+ic );
        ic.ICaptureInit();
        int i = ic.ICaptureOpen("192.168.0.200", "1234567890");
        System.out.println( "Return from ICaptureOpen = "+i);
        int purpose = 1;   // Identification, Enroll
        int whichEye = 2;  // Right, left. both
        int fedLevel = 0;  // Fake eye detection 1 = detect, 0 = dont
        int timeOut = 10000;  // Time out in milliseconds
        int auditFace = 0;  // 1: Capture face image also; 0: don't capture 
        try
        {
            i = ic.ICaptureStartIrisCapture(purpose, whichEye, fedLevel, timeOut, auditFace);
            System.out.println( "Return from ICaptureStartIrisCapture = "+i);
            i = ic.ICaptureStopIrisCapture();
            System.out.println( "Return from ICaptureStopIrisCapture = "+i);
        }
        catch (Exception e )
        {
            System.out.println( "Exception = "+e.getMessage());
        }
        i = ic.ICaptureClose();
        System.out.println( "Return from ICaptureOpen = "+i);
        
   }
}

The problem I am having is how do I instantiate and access a class rather than a function from within a dll?
How would I set up a java interfact to instantiate the class?
And, how would I access the class functions from within my main program?

I would prefer to get a JNA example, but a JNI example would work if I get some pointers on how to set
up access to dlls that contain classes and dlls that contain functions.

Thanks.