How to fit background screen in Android?

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:removed="#F555"
    tools:context="${relativePackage}.${activityClass}" >
	
    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/PoNo"
        android:layout_alignBottom="@+id/PoNo"
        android:layout_alignRight="@+id/textView1"
        android:text="PO No: "
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/InvNo"
        android:layout_alignBottom="@+id/InvNo"
        android:layout_alignParentLeft="true"
        android:layout_marginLeft="28dp"
        android:text="Invoice No: "
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <Button
        android:id="@+id/btnext"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignRight="@+id/PoNo"
        android:layout_marginBottom="112dp"
        android: önClick="btnNext"
        android:text="next" />

    <EditText
        android:id="@+id/PoNo"
        android:layout_width="169dip"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:layout_toRightOf="@+id/textView2"
        android:ems="10" >

        <requestFocus />
    </EditText>

    <EditText
        android:id="@+id/InvNo"
        android:layout_width="169dip"
        android:layout_height="wrap_content"
        android:layout_above="@+id/PoNo"
        android:layout_alignLeft="@+id/PoNo"
        android:layout_marginBottom="24dp"
        android:ems="10" />
    
</RelativeLayout>