How To Put Marker Of Special Location

I am trying to put a Marker of a special location, I have tried all the marking ways but cannot figure it out...here is my code

import com.google.android.gms.maps.SupportMapFragment;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;

[Code]....

Here is my layout...the map works i just need a marker

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"

[Code]...