Aha! Sorry I didn't appreciate that you had designed the screws to lift as well - that's a refinement that I don't think many presses have!

Once the press is finished you'll be able to get lots of practice. Ii's probably well worth while finding a printmaking course to learn the basics of grounds, the actual etching process, printing and so on. The studio will have all the materials, acids and so on. It is possible to use aluminium for plates, and etch them with a solution of sodium carbonate (washing soda) - a bit kinder than copper/nitric acid or ferric chloride.