Apps A few how to questions

[Technologx]

How do I go about alerting the user that they have a new notification on my forum? Also how do I allow the user to upload and download files from my forum? I have included the code I have I just have no idea what code I need to add and where I need to add it I'm a complete noob when it comes to doing this.

package technologx.technologx;

/**
* Created by Technologx on 12/22/15
* ©2015 Technologx All Rights Reserved
* http://technologx.fulba.com
*/

import android.os.Build;
import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.webkit.CookieSyncManager;
import android.webkit.WebView;
import android.webkit.WebViewClient;

@SuppressLint("SetJavaScriptEnabled")
public class MainActivity extends Activity {

    private WebView webView;

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        // If the Android version is lower than Jellybean, use this call to hide
        // the status bar.
        if (Build.VERSION.SDK_INT < 16) {
            getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                    WindowManager.LayoutParams.FLAG_FULLSCREEN);
        }

        // Adds Progress Bar Support
        this.getWindow().requestFeature(Window.FEATURE_PROGRESS);
        // Makes Progress Bar Visible
        getWindow().setFeatureInt(Window.FEATURE_PROGRESS, Window.PROGRESS_VISIBILITY_ON);

        // Use forum.xml as webview layout
        setContentView(R.layout.activity_main);

        webView = (WebView) findViewById(R.id.webView);
        webView.getSettings().setJavaScriptEnabled(true);

        // Adds Zoom Control (You may not need this)
        webView.getSettings().setSupportZoom(true);

        // Enables Multi-Touch. if supported by ROM
        webView.getSettings().setBuiltInZoomControls(true);

        // Change to your own forum url
        webView.loadUrl("http://technologx.96.lt/");

        webView.setWebViewClient(new WebViewClient() {
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                // Loads only your forum domain and no others!
                if (url.contains("technologx.96.lt") == true) {
                    view.loadUrl(url);
                    // Adds Progress Bar Support
                    super.onPageStarted(view, url, null);
                    findViewById(R.id.progressbar).setVisibility(View.VISIBLE);
                    // If they are not your domain, use browser instead
                } else {
                    Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
                    startActivity(i);
                }
                return true;
            }

            @Override
            public void onPageFinished(WebView view, String url) {
                // Removes Progress Bar
                findViewById(R.id.progressbar).setVisibility(View.GONE);
                // Adds Cookies. Yummy!
                CookieSyncManager.getInstance().sync();
            }
        });
    }



    @Override
    public void onBackPressed() {
        // Enables going back history
        if (webView.copyBackForwardList().getCurrentIndex() > 0) {
            webView.goBack();
        } else {
            // Your exit alert code, or alternatively line below to finish
            // Finishes forum activity
            super.onBackPressed();
        }
    }

}