For absolute beginners

There are several things required to get started with KSpigot.

Kotlin

Kotlin is requirement for using KSpigot, as it is made for use with the Kotlin programming language.

You can start learning Kotlin with the official docs or by using the Kotlin Playground.

Gradle

You should be able to use Gradle as your build system, although you do not have to understand to much of it. Probably it will even work if you just copy and paste the snippets this guide provides.

Paper

Paper is just an API, meaning that if you are able to use Kotlin, you will be able to use an API like Paper and KSpigot. Nevertheless, it is good to know at least something about the Paper API.