1. First you must create an account, do this here:
Create Account
2. Once you have an account, you can manage your credentials in the Client section of the main menu, when you have an account you will find it here:
Manage Client Credentials
3. Once you have your credentials, you can use them to get an access token, which will allow you to access the API. See how here:
Get Started
4. Finally you can explore teh endless posibillities in the docs - for that you are at the right place!