You mentioned you already have a website. What are you using for your existing website?

If you're using WordPress already for your site you could use WooCommerce. It's a plugin for WordPress so it seamlessly integrates into your site. It's bigger than all of the other platforms out there (Shopify, Magento, BigCommerce, etc) and has a ton of integrations.

If you find WordPress confusing or you don't already have it setup then looking into Shopify would be next best course of action.

I hope that helps! :)