1. Go to the Themes page in your Shopify admin panel and edit it as HTML.

Please follow the guide, if you have any troubles — https://help.shopify.com/themes/customization#view-the-customize-theme-page

2. Copy the HTML code below and paste it to the theme.liquid template:

<form class="search" action="/search">
    <input type="text" placeholder="Search" name="q" value="{{ search.terms | escape }}"  />
    <input type="submit" value="Search" />
</form>

3. Don’t forget to save the changes after you add the new HTML code. As you see on the screenshot, we’ve added our search form code to the navigation header of the store.

4. Go to the storefront and check the search box. Searchanise is working well in your store now!