Welcome to the game.
Satellites:
Satellites can be launched from Planets, Ships, and Starbase/Spacestations/Battlestations.
To launch from a ship or base, you must equip them with the component called Satellite Luancher. The more of these you have, the more you can launch per turn.
Satellites are useful for planetary defense, warp point defense, asteroid defense, and come in 3 sizes. The larger the better.
Satellites set ups can be anything you want them too be. Most players have mulitiple set ups for defense. One is Point Defense only, to take out missles, drones, and fighters. Heavy Cannon for Capital ships, and others. Medium Cannons for Smaller ships and fighters.
Mines work like satellites, but work best at warp points. Minning a planet is kinda useless IMHO, unless you planet to blockade it, or hold if for colonization later. The mines help keep the enemy fleets away from the planet.
Weapon Platforms are you planets primary defense weapon. Weapon Platforms come in three sizes and the principal holds true that the bigger they are the more they can dish out.
Again, Weapon Platforms can only be put on planets that have availible storage, and the bigger they are the few you can place on a planet. Weapon Platforms are awsome and in sufficant numbers can devastate and enemy fleet.
The same idea about mulitiple types is also true for weapon platforms as well. Heavy weapons = longer range, Missile Platforms = Capital ship doom, and Medium to short range weapons means come in close and get wasted.
I hope my wondering typing has helped you to some degree.
