It wouldn’t be that bad… you can clone a version of the wiki. A link to do that shows up below the version picker in the tree on the left.
Then you use the buttons at the top middle of the wiki pages to add a spell. Find the id of the spell on wowhead or something and you can get some of the info to fill in automatically like the name and icon and spell school.
You can look at similar spells from a dps spec to get an idea of how to implement a spell. If that isn’t enough just ask and we can help out.
There is no tutorial for making spells right now, sorry.