Activating a file:

Notepad++ allows you to open multiple files at once, but only one will be active (have focus) at any time. All files are represented on the tab bar with their filename and an icon indicating if its normal, edited or readonly (see the section about the Tab Bar for more details). Simply click on a tab to activate the file. You can also use the Ctrl-TAB and Ctrl-Shift-TAB key combinations to switch through the active files, or depress the right mouse button and use the scroll wheel (see also Switching between Documents).
If you have Multi-View enabled, only one view can be actually active, however you can see both files (see also the section about Multi-View).