I really liked this YouTube video's explanation about retargeting.
Glad to see your store coming up well! My wife and I had our first kid about a year back and I can already see the curated collection of your products (especially the New Mums Accessories collection) could have been such a time saver for us!
Its great that you are thinking about retargeting people visiting your website! This is proven to be one of the best techniques to improve your conversion rates (i.e. getting more sales from the same traffic, isn't that magic! :) )
Here is a quick summary of how this works:
Image courtesy: https://www.crowntv-us.com/
There are couple of ways in which you can run retargeting ads on Facebook:
1. Using Facebook Ad Manager directly: Over the last few years, Facebook has made it incredibly simple to use the Facebook Ad Manager to quickly create and run retargeting ad campaigns with various objectives. All you need to do is to include the Facebook pixel on your Shopify store and the rest of the configuration (like who to target, what to show them, for how long etc.) can all be done from the Facebook Ad Manager user interface. Here is a quick step-by-step walkthrough of how to do this: https://www.facebook.com/business/help/952192354843755?id=1205376682832142
2. Using retargeting apps: There are a number of Shopify apps which make it even simpler for you to run retargeting ads with a few clicks. Here is a full list: https://apps.shopify.com/browse/marketing-advertising-and-retargeting
I have heard good reviews about the RetargetApp (https://apps.shopify.com/retargetapp-facebook-retargeting)
Note that while many of these apps will help you in quickly running the retargeting campaigns, the key difference between a successful ad campaign and a non-successful one would be the messaging (content/offer) that you show to the bounced visitors. Simply showing them the product images again may not be helpful in nudging them towards a transaction. Also, its important to create separate segments of visitors who bounced from your site (based on pages they visited, products they interacted with, time spent etc.) to be able to create hyper personalised retargeting campaigns, which are bound to produce great results!
Ezra Firestone has a good Academy Course for beginners that explains the basics a store owner can follow to setup a retargeting ad in Facebook. It's a short, simple course that provides fundamental advice that almost every store should be doing. You'll be able to do what you want by the end of it.