Create ImageButton as:
In main.xml:
<ImageButton android:id="@+id/ib"
    android:src="@drawable/bookmark" <-- SET BUTTON IMAGE HERE -->
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
/>
In Code part:
ImageButton ib=(ImageButton)findViewById(R.id.ib);
ib.setOnClickListener(ibLis);
    }
    private OnClickListener ibLis=new OnClickListener(){
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            //START YOUR ACTIVITY HERE AS
             Intent intent = new Intent(YOUR_CURRENT_ACTIVITY.this,NextActivity.class);
             startActivity(intent, 0);
        }
    };
EDIT:
and second option if you want to create an image like button using Button View then Create an Custom button as:
First put your all images like for pressed,focused and default in res/drawable folder and then add an newbtn.xml in drawable/newbtn.xml as:
<?xml version="1.0" encoding="utf-8"?>  
<selector xmlns:android="http://schemas.android.com/apk/res/android">  
    <item android:state_pressed="true"  
          android:drawable="@drawable/button_pressed" /> <!-- pressed -->  
    <item android:state_focused="true"  
          android:drawable="@drawable/button_focused" /> <!-- focused -->  
    <item android:drawable="@drawable/button_normal" /> <!-- default -->  
</selector>
Finally in button XML set android:background as :
<Button    
    android:id ="@+id/btn"  
    android:layout_width="wrap_content"   
    android:layout_height="wrap_content"   
    android:text="Hello"  
    android:textColor="#ffffffff"  
    android:background="@drawable/newbtn"   <-- get button background to selector -->
    /> 
See this tutorial for Creating Custom Button with images
Creating custom, fancy buttons in Android