The easiest way to open a new document is to press Ctrl and N together. Then press Ctrl + S to save the file. The default title will be new with a number. Press Ctrl+Alt+S to get the File Save As option to rename your document. Use the Find and replace command to remove the desired text (Ctrl+H from the keyboad). NotePad++ can have a Menu Bar and Tool Bar displayed or hide them. Many like to use the keyboard commands and hide the toolbars. If the Menu Bar is open, File > New. From the Tools bar, click on the page symbol with the green + on the left side of the bar.
The full manual is available as a compressed PDF or a compressed HTML file. See: http://sourceforge.net/apps/mediawiki/notepad-plus/index.php?title=NP%2B%2B_Guides
. For either file, you will need to use your preferred zip program to extract the file. (In most Windows versions, right click on the file after saving it to the Desktop or your Downloads directory and choose Extract All.) Then use Adobe Reader or a similar program to read the PDF manual. Use your preferred browser to read the HTML version. A full list of the keyboard commands is available here: http://sourceforge.net/apps/mediawiki/notepad-plus/index.php?title=Keyboard_And_Mouse_Shortcuts
Nearly any editor will do what you want to do. In Windows, the Notepad may not hold enough lines for this. WordPad probably would work (that's the default .DOC reader). Just remember to save as plain text if you don't want to have an Rich Text Formatted document.
I hope this helps.