How do I go about setting up a website where I'll be importing a CSV file for selling products?
Muse is (a) "End of Life", what means, it isn’t develpoed any more, and (b) no application to build "dynamic", data base driven site.
You should look for a different solution like this one https://webflow.com for example.
If you don’t want to abandon Muse, you should have a close look at this eCommerce widget, which allows to integrate ecommerrce pages, which import CVS data: https://www.muse-themes.com/products/ecwid-ecommerce-store
Thank you so much.