Notepad7 is a text editor, like Microsoft Notepad, with MS Office 2010 Look and Feel. It just changes the appearance, but the main functionality is the same as MS Notepad.
Using Notepad7 is so simple, just type on textbox and save with default extension '.txt'. If you want to open '.txt' file with notepad7, just change 'Opens with' application property. To do that, right click on the text document and choose properties.