If you're running a business, it's preferable to create and manage your Facebook advertising account via Business Manager.
First head to https://business.facebook.com to sign up or login.
Then go to BUSINESS SETTINGS
Select the third option CREATE A NEW AD ACCOUNT if you don't have an existing one. You can also also ADD AN AD ACCOUNT (option 1) if you want to move an existing ad account to Business Manager.
After creating your new ad account, you'll be able to add staff members to Business Manager and assign them a role, via the PEOPLE section of your business settings.
In another article, I'm guiding you through the steps to create your first Facebook Pixel, an essential tool if you want to create custom (and lookalike) audiences + track your conversions.