如何修改畅销产品块以显示特定类别的产品？

Question

我对Magento 1.9.0.1很新，并安装了第三方主题。它在主页上有4组滑块，每组都显示不同的产品列表，如畅销书，查看次数最多等。

我试图用一个特定类别的产品列表替换其中一个（畅销商品）。根据主题作者，可以在以下块文件中完成：

<?php
class Magentothem_Bestsellerproductslider_Block_Bestsellerproductslider extends Mage_Catalog_Block_Product_Abstract
{
public function _prepareLayout()
{
    return parent::_prepareLayout();
}

protected function useFlatCatalogProduct()
{
    return Mage::getStoreConfig('catalog/frontend/flat_catalog_product');
}

public function getBestsellerproductslider()     
{ 
    if (!$this->hasData('bestsellerproductslider')) {
        $this->setData('bestsellerproductslider', Mage::registry('bestsellerproductslider'));
    }
    return $this->getData('bestsellerproductslider');
}
public function getProducts()
{
    $collection = Mage::getResourceModel('bestsellerproductslider/product_bestseller')
                ->addOrderedQty()
                ;
    $collection = $this->_addProductAttributesAndPrices($collection)
                ->addMinimalPrice()
                ->setOrder('ordered_qty', 'desc');

    // getNumProduct
    $collection->setPageSize($this->getConfig('qty'));

    if($this->useFlatCatalogProduct())
    {
        // fix error mat image vs name while Enable useFlatCatalogProduct
        foreach ($collection as $product) 
        {
            $productId = $product->_data['entity_id'];
            $_product = Mage::getModel('catalog/product')->load($productId); //Product ID
            $product->_data['name']        = $_product->getName();
            $product->_data['thumbnail']   = $_product->getThumbnail();
            $product->_data['small_image'] = $_product->getSmallImage();
        }            
    }       

    $this->setProductCollection($collection);
}
public function getConfig($att) 
{
    $config = Mage::getStoreConfig('bestsellerproductslider');
    if (isset($config['bestsellerproductslider_config']) ) {
        $value = $config['bestsellerproductslider_config'][$att];
        return $value;
    } else {
        throw new Exception($att.' value not set');
    }
}

function cut_string_bestsellerproductslider($string,$number){ 
        if(strlen($string) <= $number) {
            return $string;
        }
        else {  
            if(strpos($string," ",$number) > $number){
                $new_space = strpos($string," ",$number);
                $new_string = substr($string,0,$new_space)."..";
                return $new_string;
            }
            $new_string = substr($string,0,$number)."..";
            return $new_string;
        }
}
}

我无法看到如何根据自己的需要改变它。我知道一些PHP，但这段代码对我来说很陌生！