If you have an active Office 365 or Dynamics CRM Online account or trial you will be preset as the Global Admin for your companies account. Setting administrative rights for your company is important and should be handled by either high level company employees or the company’s tech department.
You have six admin options you can assign, Global, Billing, User Management, Service, Password and user Admin. The Global Administrator role has full access to perform any operation in your organizations opportunity. You can set user administration roles as you add users, see step 3. For more information on the Administrative Roles visit Microsoft’s Administrative Roles in Office 365 article.