Greetings, and thanks for your interest in Shopify!
While Shopify works best by hosting your online business completely, we do provide options for individuals who already have a launched website and don’t want to make a switch.
If you aren’t wanting to fully migrate to the Shopify platform your best solution would be to utilize the Shopify Buy Button. This feature allows you to add Buy Buttons to your website through your site’s code. If customers want to make a purchase the Buy Button would direct them to the Shopify checkout. The best part of the Buy Button is it’s available through the Shopify Starter Plan.
I recommend creating a free trial here and then using the documents above to test out the platform and see if it’s right for you!