Building a predictive model using the brms R package

I need assistance building a Bayesian statistical model, specifically using the brms R package in R that predicts fish habitat selection/occupancy and test whether it is linked to the predictions of the Ideal Free Distribution and the Ideal Despotic Distribution.

My objectives are below:

1. quantify how density modulates the effects of habitat selection of fish; and

2. identify the habitat characteristics that are linked to high levels of habitat occupancy.

I have all the data that is needed to do this along with an R script with some existing code.

A full Bayesian model that can test both linear and non-linear relationships along with a few plots.