App webview Android não abre

Olá a todos, boa noite, sou novo no mundo android, gostei pra caramba dessa modalidade devido ao curso técnico que estou fazendo, então pessoal estou tentando fazer com que meu app ele abra uma página da internet em seu webbrowser, poré não funciona o tablet trava aparece a seguinte mensagem de erro: Unfortunately, APP has stopped, tenho os seguintes códigos:

fragment_main_activity_merco_dummy.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivityMerco$DummySectionFragment" >

<WebView
android:id="@+id/webview1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
/>

</RelativeLayout>
MainActivityMerco.java:

package com.x_merco;

import java.util.Locale;

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.FragmentPagerAdapter;
//import android.support.v4.app.NavUtils;
import android.support.v4.view.ViewPager;
//import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
//import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.annotation.SuppressLint;
//import android.widget.TextView;
import android.webkit.WebView;
import android.webkit.WebViewClient;

@SuppressLint("SetJavaScriptEnabled")
public class MainActivityMerco extends FragmentActivity {

/** Called when the activity is first created. */

 // private WebView meuSiteWV;

 // private static final String TAG_NAME = MainActivity.class.getName();

 /**
 * The {@link android.support.v4.view.PagerAdapter} that will provide
 * fragments for each of the sections. We use a
 * {@link android.support.v4.app.FragmentPagerAdapter} derivative, which
 * will keep every loaded fragment in memory. If this becomes too memory
 * intensive, it may be best to switch to a
 * {@link android.support.v4.app.FragmentStatePagerAdapter}.
 */
 SectionsPagerAdapter mSectionsPagerAdapter;

 /**
 * The {@link ViewPager} that will host the section contents.
 */
 ViewPager mViewPager;

	@Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main_activity_merco);

 //QUANDO EU DELETO AS QUATRO LINHAS ABAIXO O APP FUNCIONA PERFEITAMENTE!

 WebView webview = (WebView)findViewById(R.id.webview1);
 webview.getSettings().setJavaScriptEnabled(true);
 webview.setWebViewClient(new WebViewClient());
 webview.loadUrl("file:///android asset/www/index.html");

 // Create the adapter that will return a fragment for each of the three
 // primary sections of the app.
 mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

 // Set up the ViewPager with the sections adapter.
 mViewPager = (ViewPager) findViewById(R.id.pager);
 mViewPager.setAdapter(mSectionsPagerAdapter);

 }

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
 // Inflate the menu; this adds items to the action bar if it is present.
 getMenuInflater().inflate(R.menu.main_activity_merco, menu);
 return true;
 }

 /**
 * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
 * one of the sections/tabs/pages.
 */
 public class SectionsPagerAdapter extends FragmentPagerAdapter {

 public SectionsPagerAdapter(FragmentManager fm) {
 super(fm);
 }

 @Override
 public Fragment getItem(int position) {
 // getItem is called to instantiate the fragment for the given page.
 // Return a DummySectionFragment (defined as a static inner class
 // below) with the page number as its lone argument.
 Fragment fragment = new DummySectionFragment();
 Bundle args = new Bundle();
 args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
 fragment.setArguments(args);
 return fragment;
 }

 @Override
 public int getCount() {
 // Show 3 total pages.
 return 3;
 }

 @Override
 public CharSequence getPageTitle(int position) {
 Locale l = Locale.getDefault();
 switch (position) {
 case 0:
 return getString(R.string.title_section1).toUpperCase(l);
 case 1:
 return getString(R.string.title_section2).toUpperCase(l);
 case 2:
 return getString(R.string.title_section3).toUpperCase(l);
 }
 return null;
 }
 }

 /**
 * A dummy fragment representing a section of the app, but that simply
 * displays dummy text.
 */
 public static class DummySectionFragment extends Fragment {
 /**
 * The fragment argument representing the section number for this
 * fragment.
 */
 public static final String ARG_SECTION_NUMBER = "section_number";

 public DummySectionFragment() {
 }

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

 return rootView;
 }
 }

}

AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.x_merco"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
android:minSdkVersion="13"
android:targetSdkVersion="17" />

<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.x_merco.MainActivityMerco"
android:label="@string/app_name" >

 <intent-filter>
 <action android:name="android.intent.action.MAIN" />

 <category android:name="android.intent.category.LAUNCHER" />
 </intent-filter>
 </activity>
 </application>

</manifest>

Estão aí meu códigos pessoal, alguém poderia me ajudar a resolver este problema! Eu quero apenas exibir uma página da web no meu webBrowser, como posso fazer isso, corrigir este erro?

Desde já grato a todos!