This is no doubt one of the many thousand posts on this subject – the beta release of SharePoint Server 2013.
Download it here.
and to accompany the install, have a read through this installation guide – http://www.microsoft.com/en-us/download/details.aspx?id=30384
Minimum software requirements for the preview are the 64 bit versions of Windows and SQL 2008 R2 with SP1.
