Julie here from Shopify Support.
It's great to hear that you're working on setting up your payment gateways. We actually have a list of payment gateways available in each country here. Did you already sign up for a free trial with Shopify? If so, did you register using an address in Singapore or Malaysia?
At the moment, Shopify Payments is available in Singapore, but unfortunately not Malaysia. If you had registered your store using a Singaporean address, then you should see Shopify Payments enabled in Settings > Payments, where you'll also see the option to finish setting up your account. If your store is registered in Malaysia, then you'll instead see a list of third-party payment gateways you'll be able to choose from.
If you plan on using Shopify Payments, feel free to refer to our help doc on how to set up Shopify Payments. There, you'll learn about the requirements for Shopify Payments, how to connect your bank account, and how to view and schedule your payouts.
If you're just getting started with Shopify, then I also recommend checking out our Essential Shopify Store Launch Checklist. Apart from setting up your payment gateways, this list will help you ensure that you've completed all the steps necessary prior to launching. I think you'll find it quite useful!
What are you selling? Aside from setting up Shopify Payments, what other steps do you need to take before launching?
If you wish to integrate one of your preferred Malaysia or Singapore payment gateway to a Shopify Store, you can also integrate them using Shopify HPSDK method.