How to get products from categories in magento?

[Kaushal Elsner]

I want to display all the products from the individual categories. I am putting my code here that what i have done so far.

<?php
	$_main_categories = $this->getStoreCategories();
	
	foreach ($_main_categories as $_main_category):
?>
		<li>
			<div style="width:593px;">
			<?php
				$_products = $_main_category->getProductCollection();
				$i=0;
				foreach ($_products->getItems() as $_product):
					if($i<3)
					{
			?>
						<img src="<?php echo $this->helper('catalog/image')->init($_product, 'small_image')->resize(80) ?>" />
			<?php
					}
				$i++;
				endforeach
			?>
			</div>
		
			<div class="lof-main-item-desc">
				<h3><?php echo $_main_category->getName(); ?></h3>
				<p>The one thing about a Web site, it always changes! Joomla! makes it easy to add Articles, content,...</p>
			</div>
		</li>
<?php
	endforeach
?>

I want to display product images only but it is giving me error like -
Fatal error: Call to a member function getItems() on a non-object in C:\xampp\htdocs \xampp\Kaushal\ r4power\app\des ign\frontend\de fault\r4power\t emplate\catalog \navigation\sli der_horizontal_ nav.phtml on line 11.