You can use the jar in the releases tab, but it is reccomended to use Maven.
You can do this by adding the following repository and dependency to your project
<repositories>
<repository>
<id>jitpack.io</id>
<url>https://jitpack.io</url>
</repository>
</repositories>
<dependency>
<groupId>com.github.TheAnt03</groupId>
<artifactId>QuestionsAPI</artifactId>
<version>1.4.1</version>
</dependency>
To learn more how to use this, read the wiki