Once you've created a shipping method, you can fine tune the calculation based on the weight of the order. Use the "+" button to add new ranges and specify which ranges will apply to which calculations. Choose a type of calculation to perform for each weight range, such as a number (flat charge), formula (arbitrary calculation based on the weight), UPS lookup (internal or via their Web site), multiply by (simple rate), or select Message to generate an error message. If you specify a formula, you can include the string "@@TOTAL@@" to represent the total weight of the order. For example, "8 + @@TOTAL@@ + 2.50".