I want to Receive a Alert Message from .net webservice.

When User Reaching the Internet Connection will receive the alert message.

that Message need to Show in my application Home page itself.

Iam new to android,Help me how to Implement this.

Let's start from the beginning:

Knowing when there's internet

1. Create a BroadcastReceiver and Register it to be triggered when you got internet connection.

2. Add the permissions needed to this kind of operation in the AndroidManifest.xml

   <uses-permission android:name="android.permission.INTERNET"/>
   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
   

SOAP Webservice communication

Here it depends on you knowledge about the webservice wrapper framework. I particularly use JAX-WS when I need to work with non-Restful Webservices. But it'll not fit to you since you'd need to code the server part with JAX-WS too.

There's a lot of frameworks to work with SOAP Webservices. See this topic as a good example to start