For some reason, you have to figure it out for yourself. There is a sample app in the v1 or v2 docs, but it's completely outdated and Spark doesn't even look like that code anymore (v7). You also have to own it before you can download it IIRC. There really aren't any tutorials on the net for actually building the app, outside of a simple basic Vue module or something that isn't very realistic (not fetching from db, etc).
If you really know Laravel inside and out it will be easier. If you look at the Laravel codebase you will get an idea on the complexity of the Spark codebase on top of it. If you want to alter anything that is built into Spark, you really have to know Vue2. You don't need to use Vue in the app you make (as they say), but if you want to customize Spark in any way you really do. Most likely you'll want to change some things.
Spark is really a mystery to me. It is a solid product with absolute shit marketing or info for it. If they had a nice 15-20 videos in a laracasts series showing how to build an app with it, I bet they'd sell 20x more than they do and I'm not exaggerating. It doesn't even have to be a complicated app. Great coders; shitty marketers. It's great to tell the features and have videos showing how to set it up, but it's basically useless without the next step showing how to actually build something with it. If you're really good with Laravel and Vue2, I'd say go for it. If not, you likely won't save any time at all and it will be a frustrating experience.
If you haven't seen this yet, this is about as good of a tutorial as exists for it: https://laracasts.com/series/laravel-spark