While the process is pretty straightforward, it has changed a couple of times in very significant ways, so detailing the full process here with no way to update it would would end up being a disservice to you so to create the account, I will guide you to the link that has the most up-to-date information on how to do it, which is https://aws.amazon.com/premiumsupport/knowledge-center/create-and-activate-aws-account/. In general, the start of the process is at https://aws.amazon.com/ and you can begin it by clicking on the yellow Sign Up or Create an AWS Account button on the top right of the screen and following the instructions: