Browse the template list or search or the template you want to edit.
Click Edit for the Code your own template you want to work with.
From this screen, you can edit the template using Mailchimp's visual designer tools or click the Edit Code button to work directly in the template's HTML.
After you're done, click Save in the lower-left corner.
Click Save and Exit in the lower-right corner of the Template Builder screen.
Changes made to a Code your own template will appear in any draft or scheduled campaigns that use the template. Before making edits to a Code your own template, make sure there aren't any draft or scheduled campaigns that could be negatively affected by your changes.
The Edit Code button is only accessible in the Template Builder. To edit the code for a template you saved from the Campaign Builder, export the template and then import it back into your account as a Code your own template. Note that you won't be able to add, edit, or remove any of the drag-and-drop blocks in the imported version.
Use the Content Studio with your custom template
The content studio keeps your files handy when you're coding your own templates. You can copy a file's source URL to your clipboard and quickly insert it into your code.
To copy your file’s source URL, follow these steps.