Notepad++ - cannot launch Firefox
Notepad++ doesn't work out of the box via Wine with the installed Firefox software.
You will need to install Firefox under Wine to make it work, using the Windows installer for Firefox. Notepad++ should then work with Firefox under Wine.
An alternative to Notepad++ is the already-installed gedit software. It does most of the same functions as Notepad++ in terms of syntax highlighting and such, and comes included with Ubuntu.