Look at the following procedure:
1. Download SQL Server 2012.
2. Open the disc image and run setup.exe.
3. The SQL Server Installation Center opens, click “Install” on the left side, then select “New SQL Server stand-alone installation or add features to an existing installation”.
4. Confirm the Support Rules, then click “OK”.
5. Enter your product key or select “Evaluation Edition”, then click “Next”.
6. Accept the License Terms, then click “Next”.
7. Check “Include SQL Server product updates”, then click “Next”.
8. A warning will appear about installing SQL Server on a Domain Controller. Ignore it and click “Next.”
9. Select “SQL Server Feature Installation”, then click “Next”.
10. Check “Database Engine Services”, “Management Tools – Complete” and anything else you need, then click “Next”.
11. Ensure the Installation Rules have passed, then click “Next”.
12. Keep the default instance name and root directory, then click “Next”. If you need a named instance, then select the name of the instance radio button and provide a name for it.
13. Review the Disk Space Requirements, then click “Next”.
14. Use the Service account for all services, then click “Next”.
Note: This not a best practice since each service should run using a separate service account.
15. Select “Windows authentication mode”, add the service account to the SQL Server administrators, then click “Next”.
16. Add the service account to the Analysis Services administrators, then click “Next”.
17. Select “Install and Configure” for Reporting Services Native Mode, then click “Next”.
18. Leave everything else as the default, then continue clicking “Next” until the installation begins.
19. Reboot the machine.