Nick here from Shopify.
You need to do a few things first, mainly planning:
What do you want? (Requirements)
How will it work? (Implementation)
How will it look? (Wireframes)
Is there an app already that does this? (Cheaper)
How much do I have to spend? (Cost, ROI)
Do I really need this? (Will all, most or only some customers benefit)
What developer will I use? (The Shopify Experts)
As you can see here, your question in the post is a bit vague. Before you develop anything new for your store, think about the above first, and have a clear idea of what your vison is.
Hope this helps!