I need to integrate a website called Store Express, did anyone have done that before ?
You could integrate it via API application.
Another option could be just to export the orders from that site into .CSV file -if this is possible, and the import them into Linnworks via Open Order import. More information in regards this can be found here: https://www.linnworks.com/support/settings/import-and-export-data/import-data/import-types/order-import
I hope this helps.
Please, let me know if you have further questions.