=+4. In activity_main.xml, add the bolded lines in the following code:

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="com.jfdimarzio.fragments.MainActivity">

android:id="@+id/fragment1"

android:layout_weight="1"

android:layout_width="fill_parent"

android:layout_height="match_parent" />

android:id="@+id/fragment2"

android:layout_weight="1"

android:layout_width="fill_parent"

android:layout_height="match_parent" />