Android : How to get value from Html in Android webview

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    WebView mainpage = (WebView)findViewById(R.id.webview);
    mainpage.getSettings().setJavaScriptEnabled(true);
    mainpage.getSettings().getJavaScriptCanOpenWindowsAutomatically();
    mainpage.loadUrl("file:///android_asset/Register.html");    
}
    }

Html Code:

Name: *Poster Title: *