I'm Miles from the Social Care team at Shopify. Are you referring to being charged for shipping on your Shopify invoice? If so, I'll explain how shipping is charged on your account.
If you're using Shopify Shipping and printing your shipping labels from your Shopify admin, those are charged on your next invoice. When your customers pay for shipping, that amount is added to your total payout, and then you're required to pay the shipping charges on your invoice. For example, let's say the customer spends $50, and they pay $10 for shipping. Once you print the label, you'll receive a charge for the shipping which you've been paid for by your customer in your payout. If you want to check the specific order, head to Orders and click on the order you printed the label for. Scroll down to the timeline and you'll find a section where your shipping label was printed. It'll be labelled "You purchased a shipping label for $xx.xx". That is the charge from the courier. If you're displaying live rates in your checkout, you should only be charged the same amount as your customer. If you've set your own shipping rates, your customer will pay the rates you've created, and you'll be charged the actual cost for shipping the item.
I'd recommend taking a look at our guide on Shopify Shipping for more information as well as our billing guide. If you'd prefer not to be charged by Shopify for shipping, then my advice would be to avoid printing labels from your admin and directly organise shipping with your local courier. That way, you can make payment to them directly.
As you've made sales already, I'd love to hear more about your marketing strategy. Are you currently doing any marketing for your store? I'd recommend checking out Shopify Compass. Shopify Compass provides you with webinars and courses on things like store design, marketing and more. It's 100% free for everyone and new content is being added all the time. This program will help you drive more traffic into your store and also convert that traffic into sales.