- In the admin menu navigate to CMS -> Manage pages.
- Click Home page to edit it.
- Enter this code substituting The category id of the category you want to show for CATEGORY_ID
{{block type="catalog/product_list" category_id="CATEGORY_ID" template="catalog/product/list.phtml"}}
To get the category id go to Catalog -> Manage Categories and click the category you wish to add to your homepage. The category id will be in parenthesis at the top (ID: XX)