Add search option to wordpress theme

You can place a search box in your wordpress theme by using
<?php get_search_form(); ?>

You can also add

<form role="search" method="get" id="searchform" action="<?php echo home_url( '/' ); ?>">
    <div><label class="screen-reader-text" for="s">Search for:</label>
        <input type="text" value="" name="s" id="s" />
        <input type="submit" id="searchsubmit" value="Search" />
    </div>
</form>

After that change the id,class or style according to your need