Is there a really basic guide for someone who knows nothing?

Hi, I apologise in advance for the very basic question. I have been doing CFD-DEM simulations with Fluent for a few years, and for some reasons I wanted to try something else. However, I know nothing about Openfoam and LIGGGHTS, and by merely reading the CFDEM installation instructions, I don't really understand what I am supposed to do to start a simulation. Are there resources or something for someone who basically knows nothing about this simulation environment (aside for the physical theory and equations)? Thanks.