Hi,
In the code above, the 2nd field is the image_select field. If you're using the Online Generator, the please follow this instruction.
You can edit the code of the 2nd field like this:
array(
'id' => $prefix . 'image_select_2',
'type' => 'image_select',
'name' => esc_html__( 'Image Select', 'metabox-online-generator' ),
'options' => array(
'value1' => 'http://urltoyourimage.com',
'value2' => 'http://urltoyourimage.com',
),
),
