To add selected products to home page, use the below code.
{{block type="catalog/product_list" name="home.catalog.product.list" alias="products_homepage" category_id="49" template="catalog/product/list.phtml"}}
The category_id="49" is the id number of the category.
For example: if you want to add a fornt_page category navigate to Category > Manage Categories care a new categori called Front Page
Get the id and replace the 49 with this id
This code allows column numbers to 4
{{block type="catalog/product_list" name="home.catalog.product.list" alias="products_homepage" category_id="49" column_count="4" template="catalog/product/list.phtml"}}