How to create a simple plugin in Neo4j?

I configured Maven and managed to run example-Plugins like FullTextIndex (https://github.com/neo4j-contrib/neo4j-rdf/blob/master/src/main/java/org/neo4j/rdf/fulltext/FulltextIndex.java).

Still I struggle to create a simple Function by myself. I want to have a java-function that can find a node by ID and return its properties.

I know I can do this in Cypher, but the target is to understand the logic of plugins for Neo4j.

So after importing the plugin i should be able to type in:

INPUT ID

call example.function(217) 

OUTPUT e. g.

name = Tree, age = 85, label = Plant, location = Munich

Thanks a lot!