I decided to start making my own campaign because I have so many great Ideas of how to add unique things to the game that the current campaigns are lacking, namely multiplayer. I’m encountering a variety of issues however because all the tutorials I can find are either outdated or so basic that they are entirely unhelpful. I figured out how to make terrain through trial and error and having done simcity type terraining before I picked up on that quick. The most prevalent issue I’m having now is that I can’t figure out how to make a new ability. I figured out how to give preexisting abilities to units but I can’t figure out how to create my own unique one. I want to make a hero unit that can place a turret like Swann’s flaming betty but with unlimited duration and not a flame turret. I also want to give him an ability where he can place mines like spider mines that work like spider mines but can also be placed on rocks to destroy them (I want the mines to be the only thing that can destroy rocks in my map). Lastly I want to arm a point defense drone with a marine-like weapon and make it passively follow my hero as a kind of pet. The editor is not as easy to use as they say and any help is appreciated! 
You will get help for sure, but at some point, you may feel this help to be temporary. If you are willing to make your own campaign, it is noble, but you have to master the data first. Of course, I read you loud and clear when you say there are not many tutorials, which is why I propose to you to find the Sc2 Mapster community (a one I’m hurting myself to try to have Blizzard aknowledge them). They have a discord community, which will answer your questions to the best of their knowledge.
Regarding your demand on making this ability, it is quite possible, it just takes time. Everything takes time, because there are a lot of details. I would also presume that showing you how will have you inevitably lose certain details on how I did.
That being said now, I can give some mentorship if you can join the Sc2 Mapster discord. Just type SC2mapster Discord on their website (I can’t include links here sadly). Look for Wonder Rem in the list of people and contact me in private (just remind you are from the forums).