I'm Miles from the Social Care team at Shopify. I've used Gelato myself and am happy to help you out with this. The great thing about Gelato is you won't need the API code to get anything done. If you do run into any issues with the below instructions, you'll need to contact Gelato directly as they will be able to help out.
Once you're ready to launch, have you got a marketing plan ready to go? I 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.
Have you heard about the Shopify Blog? It's got loads of great content on ways for you to drive sales into your store. I've got some great recommendations below that I'd recommend taking a look at:
Driving Traffic but No Sales?
* We give you 13 steps to improve your conversions.
* Who is your target audience, and does your sites look and feel cater to them?
* Is your business trustworthy? (Also see the next recommendation below for more on this)
The 39-Point Store Trust Checklist
* Work through a checklist to make sure your store is trusted by potential customers.
* Look at the "nice to haves" vs "must-haves" in your store.
* Do you have essential information for your customers to view, like policies?