By default when a new user is created in Active Directory the object will be created under the top level User container (CN=User), similarly when a computer is created it will be created in the top level Computers container (CN=Computers).
If you would like to change this behaviour then this is how.
Note: Your domain functional level must be at at least Windows Server 2003
First create your desired Organisational Units for both Users and Computers.
Next you will need to find the DN’s of your OU’s, if you are unsure how to find these take a look at this article Active Directory: Finding and Copying the DN of an Object using LDP.exe
Either on you computer or on a domain controller run the below commands to make the changes.
To Redirect Users
To Redirect Computers
If your DN contains spaces etc you will need enclose the DN with quotes.