Hi,
You're probably better off asking this question in the FreeCAD forum rather than here. When you do ask there, give some details and screenshots showing exactly what you're trying to do.
But, FWIW, I've been using FreeCAD on Windows 7 & Linux machines, and can select lines and faces. I suspect your problem is that you're not switching FreeCAD to the right "Workbench". Understanding these workbenches is necessary to use FreeCAD. There are some good step-by-step tutorials on the FreeCAD site.
Frank