srpd.m123 if you are new to Admin role and you are unfamiliar with where to run the code, maybe a Maintenance Plan would be best for you. You can use the Maintenance Plan Wizard if you do not see what you are looking for. In SQL Server Management Studio, Under Management, right click on Maintenance Plans and select Wizard.

If you are strapped for space, you will want to perform the cleanup step first and then the backup. Please make note that you will need to be on Service Pack 2 or higher for SQL Server 2005 to clean up old backups correctly.