Software depends there isn’t a wrong or best programs to start designing or modelling there are variety of software you could start making models or graphic designing. Blender is a good software to get started because it’s a open source it’ll take time if your wanting to learn the workflow and curve around whatever program you choose to learn in!
I would recommend blender gurus beginner tutorial (donut & mug one) is a great place to start, it’s informative in terms of learning the basic tools, techniques, and workflow of blender. He also goes into more depth and explains a lot you could even take notes.
Keep learning how to use blender as its very useful and free, you could make a bunch of builds or models with blender, however it takes practice and patience to get the hang of that software.
If your willing to learn modelling i would recommend taking a look at this thread, it includes useful information and tips to getting started. (Try taking notes/ writing them down in a notebook so you could use those later down the line).