How do I create a brand widget for my Shopify store?

Login to your Shopify admin dashboard. On the left-hand menu, click on Themes in the Online Store section. Choose the theme to modify and click the Actions menu and choose Edit code. A list of template files will appear on the left side of the theme code editor. Choose the file named ‘theme.liquid’. Locate the area in the chosen file where the widget code is to be added. Put a piece of your widget's code there. After you add the code, click the Save button to save your changes.