If you have revit 2013 installed, the content should already be there.
If revit 2013 is installed without the content, do the following:
1- control panel.
2- uninstall revit 2013.
3- add content.
4- select your preferable library.
5- choose the default.
Regards,
Ali Al-Hammoud
Structural Design Engineer
MZ & Partners Engineering Consultancy