Good point, we should really update this tutorial for Nv2.0! In Nv2.0, the editor is no longer in alpha state, so all you need to do is log in (creating an account is completely free) and you can see a "levels" link on the main menu that takes you to the levels page, where you can browse levels. There's also a button that opens the editor in the top right hand corner of the page. Enjoy!
Needle Tatting A Necklace
How to Add User Levels from NUMA to Your Copy of N Using NumADD Firefox AddOn