Download the installation package from the link provided in your registration download e-mail. (Request download here)
On the Exchange server that will serve as your migration server, install the Office365Migrator setup package.
From the start menu, choose more applications > Office365Migrator.
Sign-in to the Office365Migrator application using an account that has local administrative permissions on the server where Office365Migrator is installed.
Click Configuration in the navigation pane, bottom-left.
In the Exchange Online configuration section:
Enter the username and password for an Office 365 Global Admin account. Note: This account should exist in Office 365 only and not be synchronized with Active Directory.
In the Exchange On-Premises configuration section:
Enter the name of the Exchange Server that will serve as the server from which mailboxes will transit to Exchange Online.
Enter the username and password of an Active Directory account that has both Active Directory and Exchange administration permissions
Enter the External DNS name of Mailbox Replication Service that was defined during the configuration of Exchange Hybrid.
In the E-mail routing settings section:
Enter the name of default domain name to be assigned to mailboxes migrated to Exchange Online.