Make a PUT request to https://api.bigcommerce.com/stores/ikiuocf6r8/v3/content/widget-templates/{widget uuid}

with the following headers

X-Auth-Client {{auth client secret }}

X-Auth-Token {{ auth token }}

Accept: application/json

Content-Type: application/json

Then put the widget code in the body. For example

{   
    "name":"Innovator", 
    "template": "<div class='innovator' data-photo='{{ image.src }}' data-photo-alt='{{ image_alt }}' data-title='{{ title }}' data-name='{{ name }}' data-bio='{{ bio }}'><div class='innovator-image'><img src='{{ image.src }}'/><div class='innovator-alt_text' data-alt-text='{{image_alt}}'></div></div><h3 class='innovator-name'>{{ name }}</h3><h4 class='innovator-title'>{{ title }}</h4><div class='innovator-bio'>{{{ bio }}}</div></div>",
    "schema": [{
        "type": "tab",
        "label": "Content",
        "sections": [
            {
                "label": "Image",
                "settings": [
                    {
                        "type": "imageManager",
                        "id": "image",
                        "default": {
                            "src": "",
                            "type": "IMAGE_MANAGER"
                        }
                    },
                    {
                        "type": "input",
                        "label": "Alt Text",
                        "id": "image_alt",
                        "default": ""
                    }
                ]
            },
            {
                "label": "Name",
                "settings": [{
                        "type": "input",
                        "id": "name",
                        "default":""
                    }]
            },
            {
                "label": "Title",
                "settings": [{
                        "type": "input",
                        "id": "title",
                        "default":""
                    }]
            },
            {
                "label": "Bio",
                "settings": [{
                        "type": "text",
                        "id": "bio",
                        "default":""
                    }]
            }
        ]
    }]
}