Per Microsoft KB 324753:
Adding Users and Computers to the Active Directory Domain
After the new Active Directory domain is established, create a user account in that domain to use as an administrative account. When that user is added to the appropriate security groups, use that account to add computers to the domain.
- To create a new user, follow these steps:
- Click Start, point to Administrative Tools, and then click Active Directory Users and Computers to start the Active Directory Users and Computers console.
- Click the domain name that you created, and then expand the contents.
- Right-click Users, point to New, and then click User.
- Type the first name, last name, and user logon name of the new user, and then click Next.
- Type a new password, confirm the password, and then click to select one of the following check boxes:
* Users must change password at next logon (recommended for most users)
* User cannot change password
* Password never expires
* Account is disabled
6. Review the information that you provided, and if everything is correct, click Finish.
2. After you create the new user, give this user account membership in a group that permits that user to perform administrative tasks. Because this is a laboratory environment that you are in control of, you can give this user account full administrative access by making it a member of the Schema, Enterprise, and Domain administrators groups. To add the account to the Schema, Enterprise, and Domain administrators groups, follow these steps:
- On the Active Directory Users and Computers console, right-click the new account that you created, and then click Properties.
- Click the Member Of tab, and then click Add.
- In the Select Groups dialog box, specify a group, and then click OK to add the groups that you want to the list.
- Repeat the selection process for each group in which the user needs account membership.
- Click OK to finish.
- The final step in this process is to add a member server to the domain. This process also applies to workstations. To add a computer to the domain, follow these steps:
1. Log on to the computer that you want to add to the domain.
2. Right-click My Computer, and then click Properties.
3. Click the Computer Name tab, and then click Change.
4. In the Computer Name Changes dialog box, click Domain under Member Of, and then type the domain name. Click OK.
5. When you are prompted, type the user name and password of the account that you previously created, and then click OK.
A message that welcomes you to the domain is generated.
6. Click OK to return to the Computer Name tab, and then click OK to finish.
7. Restart the computer if you are prompted to do so.
A more visual instruction for this process can be found here.