SHIFT-right-click in the right panel
Put the mouse cursor in the right panel of the Explorer window. Make sure no file names are highlighted. Left-click in a blank space in the window to un-highlight any file. (If you just created the folder, there will be no files, so this is not needed.)
SHIFT-RIGHT-click in the window.
A menu will pop up. Click on "Open Power-shell window here". (Depending on your revision of Windows, this may be some other similar command window.)
The command prompt is the part PS C:\JavaSource>
In this minimalist environment, you enter commands to the OS by typing them after this prompt. To start Notepad, type notepad after the prompt. Hit "enter".
What is the clipboard in Windows?