How to Set Up Flat Rate Shipping for Shopify
To set up flat rate shipping:
On the Shopify home page, select Settings located at the bottom left corner of the page.
From Settings page select Shipping.
From the Shipping page select Add Shipping Zone option.
From the Add Shipping Zone page, select Add Rate next to Price Based Rates.
From the window that pops up you can select the name, set a minimum order price, maximum order price, and set the Rate Amount.
When you are finished editing the Price Based Rate, select Done.
Lastly, select Save at the bottom of the page to apply the changes.