Ted here from Shopify, thanks for reaching out to us!
How are you finding Shopify so far? I've taken a quick look at your online store and it looks like you haven't connected to a payment gateway successfully as of yet. Can you please log into your Shopify admin and in the Settings > Payment providers section, could you double-check to see if you are connected with Paypal? If your account looks like this screenshot, you will just need to click the Activate Paypal Express Checkout button. This guide will also help.
Please let me know how this goes!