Android : How to run a Android Program?

i just installed Android Studio in my linux machine

this is my simple android code :

package com.example.noob.ss;

import android.os.Bundle;
import android.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;


import com.example.noob.ss.dummy.DummyContent;

/**
* A fragment representing a single photo detail screen.
* This fragment is either contained in a {@link photoListActivity}
* in two-pane mode (on tablets) or a {@link photoDetailActivity}
* on handsets.
*/
public class photoDetailFragment extends Fragment {
/**
 * The fragment argument representing the item ID that this fragment
 * represents.
 */
public static final String ARG_ITEM_ID = "item_id";

/**
 * The dummy content this fragment is presenting.
 */
private DummyContent.DummyItem mItem;

/**
 * Mandatory empty constructor for the fragment manager to instantiate the
 * fragment (e.g. upon screen orientation changes).
 */
public photoDetailFragment() {
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    if (getArguments().containsKey(ARG_ITEM_ID)) {
        // Load the dummy content specified by the fragment
        // arguments. In a real-world scenario, use a Loader
        // to load content from a content provider.
        mItem = DummyContent.ITEM_MAP.get(getArguments().getString(ARG_ITEM_ID));
    }
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_photo_detail, container, false);

    // Show the dummy content as text in a TextView.
    if (mItem != null) {
        ((TextView) rootView.findViewById(R.id.photo_detail)).setText(mItem.content);
    }

    return rootView;
 }

}

and when i run this program,i just got a message in my Virtual machine that is "unfortunatly ss(my program name) has stoped "

and i got this error ,how can i fix this?

error:

  1648-1648/com.example.noob.ss E/AndroidRuntime﹕ FATAL EXCEPTION: main