To edit Shopify template files, follow these steps:

1. Log in to your Shopify account and go to the Online Store section.

2. Click on the "Actions" button next to the theme you want to edit, and then click "Edit Code".

3. In the code editor, you will see a list of files on the left-hand side. Each file represents a template that controls a specific area of your store.

4. Find the template file that you want to edit. For example, if you want to edit the product page, look for a file called "product.liquid".

5. Click on the file to open it in the code editor.

6. Find the section of the file that you want to edit. This can be done by using the search function or by manually scrolling through the file.

7. Make the necessary changes to the code.

8. Click the "Save" button to save your changes.

9. Preview your store to ensure that the changes have been applied as expected.

Note: It is important to be careful when editing template files as any mistakes could break the functionality of your store. Always make a backup copy of the original file before making any changes and test any changes on a staging site before deploying them to your live store.