Don't get discouraged. As soon as you get all these little things sorted in your brain, it just clicks.
This. In all of my practice games so far I've been to scared to delve into combat and managed to avoid meeting any NPC so there was no chance anyway. I decided to give the system a try in this game, creating multiple races on a planet. I started by having a small nuclear exchange between Russia and China. I made a number of mistakes in designing my first combat ships (forgot active sensors, didn't put power plants on the beam ships - the first corvette (which was developed by JAXA) had to be refitted twice to incorporate both those. I just named them the "stage I" "stage II" and "stage III" and RP'd that they were in a rush to get them built for show and added in essential systems later) but now I'm getting the hang of it and it's honestly fascinating. The 2 corvettes shot down a number of conventional ICBM's from China, but then fell to the powerful "size 21 drone". These were developed by the Chinese as fast, powerful weapons that could be launched from regular ICBM silos. They arrived at the corvettes within 5 seconds, the corvettes didn't even have a chance to target them let alone fire.
Playing around with the various weapons has been entertaining so far and I feel I understand how combat works now. I have some idea of how to design ships for combat and how to tell them to shoot things. You can learn a lot about combat by doing it in a controlled environment with a controlled opponent.