The "Select" button is rendered as an input element with the CSS class ".ruBrowse". You can try overriding the CSS like below to override the default appearance.
hi princy. thanks for helping me. But after applying the CSS, its not looking like a button. The added image and text is only displayed and found the sprite image being replaced. So I thought of adding as an image button but now the text is interfering and giving it a weird look.