In Windows, there's a "edit" menu option when you right-click on a unkown file-type. When you select it, the sucky Notepad thing will open that file.
How can I change Notepad with another editor, like Notepad2 ?
You may use Notepad Replacer to exchange notepad with an editor of your choice, this is the easiest way i know.
you can download notepad++
then Right click on file go to property go to open with
As i think you won't find notepad++
then click on Browse go to program file->notepad++->notepad.exe
then select this file as default application to view the content
Now you have done and whenever you open any text document it get opened in notepad++ or whatever texteditor you have selected.