how to add custom classes and div to drupal search form.. i want to change complete layout of the block [duplicate]

Question

I want to set following HTML layout in my search form.

   <div id="sb-search" class="sb-search">
<form>
    <input class="sb-search-input" placeholder="Enter your search" type="search" value="" name="search" id="search">
    <input class="sb-search-submit" type="submit" value="">
    <span class="sb-icon-search"><img src="<?php echo $theme_path;?>/images/search_icon.png" alt=""></span>
</form>

but when i render the form using module invoke i got all classes and divs that are associated with search block,i want the above HTML to be applied to my search block.