@dty That very nice that you are interested in BilevelJuMP.
@odow Just left excellent suggestions, I strongly recommend following them.
Starting simpler is the way to go. If you are having trouble, you might start with single level problems directly in JuMP, it is more user proof and mature.
Once basic stuff work in JuMP, porting to BilevelJuMP should be easy.
Last, but not least, if you can follow PSA: make it easier to help you it will be much easier to help.