use the below as drawble file,let suppose button_bg.xml
<shape android:shape="rectangle">
<solid android:color="@android:color/transparent"/> --> change any color here accorring to your requirement,and this will the background of your button.
<corners android:bottomLeftRadius="8dp" --> use this if you want to make button corners rounded.
android:bottomRightRadius="8dp"
android:topLeftRadius="8dp"
android:topRightRadius="8dp"/>
<stroke android:width="1dp" --> use this if you want button border.
android:color="#9c9a9b"/> --> change any color here accorring to your requirement
Here is your button code
Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_below="@+id/button2"
android:minHeight="106dp"
android:background="@drawable/button_bg" -- > set the above file like this.
android:text="Button" />
Or simple you can make a image and put that in your drawable folder and can set as button background like:
android:background="@drawable/YOUR_IMAGE_NAME"