To add to the above (most of which I wasn't aware of, so thanks): start out with TinkerCAD + PrusaSlicers. TinkerCAD is super easy to get started, but does allow for fairly precise building blocks. PrusaSlicer has a bit of a learning curve, but once you know there's almost nothing you need to change other than level of detail (nozzle setting) you should get pretty far on your own. I learned a bunch of printing wisdom from /r/fixmyprint, one wisdom of which is that given a seemingly simple problem there are always four different solutions proposed cuz overstimating internet users. But the good one is usually in there. With infrequent use of the printer, there's a good chance the nozzle will clog and your printer will not print a single good layer. There's a few YouTube videos on how to solve that, it looks hard but it's not that hard once you're comfortable opening up your printer head.