Changes to the Homepage

[Benix89]

Hi, 
I am making changes to the home page of my e-commerce. I want a blank page with a google search at the design center. I set to "empty" the layout to have a blank page and I moved the "search" (default) in the bottom.

Now, I would like to make changes to the "search":

I went to read the template /app/design/frontend/base/default/template/catalogsearch/form.mini.phtml

This is the code inside ( no comments ):

<?php
$catalogSearchHelper =  $this->helper('catalogsearch');
?>
<form id="search_mini_form" action="<?php echo $catalogSearchHelper->getResultUrl() ?>" method="get">
    <div class="form-search">
        <label for="search"><?php echo $this->__('Search:') ?></label>
        <input id="search" type="text" name="<?php echo $catalogSearchHelper->getQueryParamName() ?>" value="<?php echo $catalogSearchHelper->getEscapedQueryText() ?>" class="input-text" maxlength="<?php echo $catalogSearchHelper->getMaxQueryLength();?>" />
        <button type="submit" title="<?php echo Mage::helper('core')->quoteEscape($this->__('Search')) ?>" class="button"><span><span><?php echo $this->__('Search') ?></span></span></button>
        <div id="search_autocomplete" class="search-autocomplete"></div>
        <script type="text/javascript">
        //<![CDATA[
            var searchForm = new Varien.searchForm('search_mini_form', 'search', '<?php echo Mage::helper('core')->jsQuoteEscape($this->__('Search entire store here...')) ?>');
            searchForm.initAutocomplete('<?php echo $catalogSearchHelper->getSuggestUrl() ?>', 'search_autocomplete');
        //]]>
        </script>
    </div>
</form>

From here you can change the size?

I was advised to apply a style to html element line or CSS files, but I have not understood well. Can you give me a hand?