I have being playing around with the software for a couple of days now and managed to do simple stuff. I noticed that the software is shortcuts oriented and that does not make it intuitive. I found some resources on this message board and some videos on Youtube, but that only covers the basics.

If only I could I would help and make the documentation, but I don't understand the software enough!

My concern is that users will eventually get frustrated and abandon their project for a lack of understanding.

To the author: Your software is amazing but it became complex. My suggestion would be to make a 1-hour Youtube video where you cover every items and explain how to use them.

Hi! Documentation and especially tutorials is lagging a bit behind, i'm aware and trying to do something about it as often as i can find the time to.

Sadly, there's only one of me, and since the project is free, i don't have the resources available to both develop it and make videos consistently. 

More videos are coming eventually, but in the meantime, i recommend:
-keeping up to date with the changelog.txt, where all the features are thoroughly introduced in a chronological order. It can take some searching if the feature is old, but it's essentially all there. 
-make use of the cheat sheets and keep them close at hand: look for the Cheat sheets folder. They're also available directly on the side bar in the itch main page. 
-read the other help docs (you can find them in the Documentation folder: especially hotkeys_main_editor and hotkeys_CHR_editor are important)
-join the NESdev discord and make use of the graphics-workshop and graphics-assistance channels there. There are several longtime users there who can help and i try to check by as often as i can to answer questions personally. It's become the de-facto hub for nexxt users. 
-there are a few 3rd party NES development oriented tutorials that mention NEXXT and how to do specific things. I wish there was more of that, but some do exist.  

And lastly, while strictly voluntary, i encourage longstanding users to join my patreon to help fund making the tool better / its documentation better. Sometimes, i also post specialized usage articles there, though the patreon posts are as much about nexxt as about my own graphical work. The patreon-associated discord is yet another space i monitor for personal user help.