So, first things first, you'll need to download N
. It's free!
When you unzip the archive, you'll notice there are a bunch of files included with your download. One of these is the N Editor Manual. This is a comprehensive guide to using Ned, the N level editor -- you should definitely give it a read. You can view or download the .doc version here
So when you're finished reading through that awesome and informative manual, open up N. At the moment, Ned is still in the early stages of life, so it's a little rough around the edges: too rough to include directly from N's main menu.
At the main menu screen, press tilde (~ ) or the vertical bar key ( | ) to pull up the debug menu.