While I'm not an ANSYS representative, I am happy to read that someone of your age is interested in such a challenging topic and wanted to provide some insight.
Before attempting any simulation, there's quite a simple first step... read! Read a LOT of papers on the subject. I can point you to a few papers from my past colleagues that have done exactly what you are setting out to do. These papers can be quite challenging to go through with only a general physics understanding at the moment, but don't be deterred! There is great reward for those that persevere to understand this topic! I am sure with time and comittment it will be no problem for you to understand. From these papers, you can look at their references and find yourself down a "rabbit hole" and have a LOT of material to read.
In parallel, you can start simple with tutorials you find on the web. That way, you will get acclimated to the tool and not bogged down in the workflow of the tool. Remember, that LS-DYNA is just a tool and it is only as good as the information you put into it.
Next, raise the complexity slowly by finding a paper that is simple enough to model, but is in the right direction of the end model you want to create. By finding a paper that is simple (but somewhat similar to the end model) AND with results, you can see if you can replicate the same results. Then, as you get more and more comfortable with what is happening you can attempt to start expanding this model to what you want. It should be viewed as an iterative process and build complexity slowly to ensure the model is performing as expected each time. Which leads me to one of my last points... before you open your results, you should have performed some calculations or have some intuition of what you expect the solution to look like prior. Simulations solve equations, but it is the user that must have the insight to know what is correct or not.
I know this is quite a long, drawn out process, but this is the modeling process. It gets faster the more you learn about the subject. I'm sure there are other nuances I am forgetting that other modelers in this forum can add, but I think in general, all modelers follow a similar path.
Best of luck,
Here are some papers:
 Kshitiz Upadhyay, Ahmed Alshareef, Andrew K. Knutsen, Curtis L. Johnson, Aaron Carass, Philip V. Bayly, Dzung L. Pham, Jerry L. Prince and K. T. Ramesh, Development and validation of subject- specific 3D human head models based on a nonlinear visco-hyperelastic constitutive framework, 2022
 T. Wu, J.S. Giudice, A. Alshareef, M.B. Panzer, Chapter 7 - Modeling mesoscale anatomical structures in macroscale brain finite element models, Multiscale Biomechanical Modeling of the Brain, Pages 103-118, 2022,
 Ahmed Alshareef, J Sebastian Giudice, Jason Forman, Daniel F Shedd, Kristen A Reynier, Taotao Wu, Sara Sochor, Mark R Sochor, Robert S Salzar, Matthew B Panzer, Biomechanics of the human brain during dynamic rotation of the head, 2020, https://doi.org/10.1089/neu.2019.6847