Simple Method..
From the desktop, right click the Computer icon.
Choose Properties from the context menu.
Click the Advanced system settings link.
list item Click Environment Variables. In the section System Variables, find the PATH environment variable and select it. Click Edit. If the PATH environment variable does not exist, click New.
In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable example(C:\Qt\Mingw32\bin). Click OK. Close all remaining windows by clicking OK