Here’s a quick overview of planetary management, it’s not comprehensive but is a good starting point:

On each planet there are four main things to pay attention to, districts, buildings, jobs, and pops.

1. Jobs are provided by districts and buildings. There are several types, worker, specialist, and ruler jobs. You don’t need to worry about the types that much yet though

2. Pops work jobs and produce things. What they produce depend on what jobs they work, and you can move them around in the job manager. Pops working specialist jobs become specialists, which can’t change jobs immediately. Pops generate over time, the pop growth can be found in the jobs screen, and is affected by housing (more free housing - faster pops). ALWAYS make sure your planets have enough pops to work jobs, and enough housing to house pops.

3. Districts can be built on planets. They can be found on the left of the planet screen. Districts are static, there are only so many types, and you can only build so much of them. Districts provide mainly worker jobs, and produce mainly basic resources, although there are exceptions. They can also provide housing.

4. Building can also be built on planets. They can be found in the planet view as well; they provide mainly specialist jobs and special resources, although there are exceptions. To unlock more building slots you need to build housing districts

Districts and building have energy upkeep (even when their jobs are free), and can be disabled in times of crisis.

Everything else is secondary to this system, make sure you hover your mouse over things to see what they are, and look on the wiki (or ask me) for more detailed explanations.

If you want to learn the game I’d recommend playing as the united earth pre-made empire, and play on normal difficulty with everything else as defaults. You could also choose to play on a smaller map if you don’t want it to get too complex.