If you are a new Oracle Cloud Applications user, you'll likely receive a Welcome email after your order is processed.
The Welcome email will provide you with information to sign in to your new account; after you sign in, you can activate your services by creating a new service instance. See Create an Instance.
However, there are cases where Oracle configures and creates your Cloud Application services for you. In those cases, you'll receive a separate email that asks you to activate your order. If you receive such an email, follow the instructions in the email to provide some additional required information and activate your Oracle Cloud order. You'll then receive a follow-up email with the information you need to sign in and start using your Cloud Applications. See Activate Your Order.
Next step: Sign In to Oracle Cloud For the First Time.