Hi @jillwright86
Welcome to the Klaviyo Community! Thank you for posting your question!
My first question to you is, do you have set up on your website the ability for customers to choose to subscribe to your marketing? This could be way of popup, form, or check-box in the checkout process.
To understand more about who has actually subscribed and who is in your database that has come via purchase or other means, I would suggest reading these two really helpful articles.
I hope this provides some guidance.
Kylie