Check out this guide to quickly (15-25min) learn:
How to solve a knapsack problem with OptaPlanner.
OptaPlanner core concepts and how to apply them in a use case
How to expose your service as a REST application on Quarkus.
How to deploy that application in the cloud on OpenShift.
The optaplanner-training teaches OptaPlanner through a number of labs. Each lab has an assignment with clear goals, initial code and a solution.
Download and unzip
instructions/training.html and follow those instructions.
The source code which generates that training zip is in the optaplanner-training GitHub repository.