Awhile back, I think it was in 2.7 and previous, there was an option to have Notepad++ in the context menu. If you right clicked the file, it said Notepad++ and if you clicked that it opened the file in Notepad++. I thought this still was in 3.2, but since I tried running it on a fresh installation of Windows, that context menu was gone. :-O I really miss this and I hope this missing functionality comes back in a newer version. :-)
You can take advantage of "Open With". Right click on your file, select Open With, Browse for Notepad++.EXE. It's up to you whether or not you want to Open With every time or just this once. Once N++ has been registered in the Open With list, it will show up for many file types.
Please see :