How to buy USDT at official rate?

I'm curious, how does one go about purchasing USDT at the official rate? Is there a specific platform or process that needs to be followed? I'm new to the world of cryptocurrency and finance, so any guidance or tips would be greatly appreciated. I'd like to ensure that I'm getting the best possible deal and not overpaying for my USDT. Can you walk me through the steps involved in this process?