Important note:
1. To import demo, you need to install theme file to your store. Follow this guideline to upload zip file.
2. Shopify only allows the download of theme demo data and assets uploaded within the theme, such as settings, slideshow images, banners, and image galleries. However, content uploaded through the Shopify Dashboard (like products, pages, blogs, menu navigation, and metafields) cannot be packaged and included within the theme. Therefore, you need to use your store's specific information for these elements.
Please make sure that you have unzipped the theme package that you download on Theme Forest before upload it to your store. Otherwise, you will get the issue: zip does not contain a valid theme: missing template "layout/theme.liquid". Then please upload Theme_x.x.zip file to your store.
Theme" - it means name of your theme such as Kalles, Basel, Gecko, Unsen, Ecomus and Ocolus.

You need to upload 2 files Settings_data_json and Index_json of the Demo that you want.
Notice: You must install Sublime Text (or other editor softwares) to your device in order to open index.json and settings_data.json. You can click here and choose the suitable Sublime Text version to install.
When you complete the import file, you need to active the theme with your license code.

Note: Kalles and Unsen's demo in EComposer is available. However, the Demo EComposer library is not yet fully available. We are currently in the process of updating it. Therefore, for any Demo that is not yet available, please use and import the theme through Shopify - Online Store - Themes.
I have theme of The4 installed and full features, why do I need theme for EComposer? Theme's The4 is of great quality, however EComposer was not developed to replace Theme's The4. It was made to fix Shopify editor problems, with Theme's The4 you can only customize everything the theme or Shopify allows but with Theme's The4 EComposer you are free to change the layout that you want.
When should I use Theme's The4 EComposer? When you have a high need to build landing pages or about, contact... at your discretion. You can absolutely use EComposer to create those pages.
I just want to use Theme's The4 is that possible? Absolutely, if your need is everything Theme's The4 has then just use it. Theme's The4 EComposer is only recommended when you have high customization needs, and want more advanced functions (like upsell extensions and high-quality layouts...). To use Theme's The4 EComposer, you are still required to install Theme's The4.
What is EComposer better than Shopify editor? It's pretty hard to explain it all here, you can try the demo at https://demo.ecomposer.app. Some outstanding powerful features can be mentioned such as a diverse library of libraries (you can combine them with Theme's The4), an extension store that allows you to have advanced features, a flexible drag-and-drop system, Various elements that allow you to build anything, the auto-save function allows you to avoid losing your work, easy to use custom fonts.....
Please follow the existing tutorial on activating the theme here.
Go to the EComposer link from the Shopify app store and install it

Please follow this quick guide from EComposer team to understand this step.
Please follow this video below: