Question: How to send a image or a file using the web service to the server ?

Answer: 
Here is a good example of how to send a file using NuSOAP:

<http://web.imkrisna.com/june/news/simple-file-transfer-using-nusoap/>
The web service's documentation should specify the necessary format, which will probably involve base64 encoding the image data. You would do whatever encoding the web service requires and then pass it to nuSoap in the same way you already do for text.