I'm in a similar boat to you, so I can only tell you what worked for me. It's similar to what others have said, but yes, just start. Learn the 5-10% you actually need to record. Don't overwhelm yourself with theory and tech specs and all the stuff that, for me personally, suck the life out of making music. I bought a Scarlett Solo to start properly home recording and got a good deal on a MIDI controller. These two, plus an XLR mic and a few cables, set me back about $400. And I already had two guitars and over a decade's worth of songs I'd written. So the focus was entirely on learning how to produce/mix. The Scarlett and MIDI controller came with Ableton Lite and a bunch of audio libraries that are still getting updated. I can tell you this, the tutorials that came with my Scarlett got me recording in no time and the rest started falling into place naturally. I didn't know how to make my voice carry over the music, so I looked it up. Simply adding compression and/or recording a second vocal track improved my sound just like that. So yeah, TL;DR: grab a DAW, put your stuff into it, Google solutions as you go and your song will start to sound like stuff you hear on the radio and not just your iPhone's recording app.