Normally many small apps require you to have .Net framework installed on your PC to run in their easy environment. So its really essential for you to have this installed on your PC, so if you are on Windows XP, Vista or Windows 8 than you have to manually download and install .NET Framework on your PC.
But the bad part is when you download it using Microsoft's official website than they normally provide you with a online installer that downloads files through active internet connection, so if you do not have internet than it is not possible for you to get it installed on your PC, so what if you need an offline installer well Microsoft provides that too.
So now just grab the offline installer from the link provided on right, it's a simple setup file of approx. 50MB so download it and simply run it that's it, it will install on its own.
So now with this every application that requires will run easily and smoothly. So make sure that you restart your PC once after installation to make installation perfect.