There are various ways to configure your store's shipping requirements. Your store has the ability to calculate shipping using the following methods and combinations:

Free Shipping: Product specific setting to not apply any shipping charges.
Flat-Rate Shipping: Product specific setting to apply a fixed rate for a product.
Carrier-Calcluated Shipping: Carrier-Calculated shipping is for US or Cananadian based stores and obtains rates directly from the following shipping providers : USPS,UPS,FedEx and Canada Post

Your store's default shipping method is Carrier Calculated and you choose a default carrier in Settings>Shipping Settings.  You can set product level shipping methods for each of your products on the Shipping tab of each product.  Product level shipping settings will override the store's default shipping selection.

How to use flat rate shipping
How to use carrier calculated shipping
How to use order total based shipping
How to only use carrier-calculated rates for international shipping