IDIOT'S GUIDE TO FED2
Designing and constructing your very own planet makes you a Founder, but then you need to run your planet's economy. You need to keep your population happy, by ensuring they have enough of all the things they need to live, and you need to make sure the planet's treasury remains healthy, by selling off the things the planet has a surplus of. To do this, you will need to work closely with CEOs and encourage them to build factories that use as inputs the things you have in excess, and produce an abundance of the things you are short of.
You will also need to encourage Merchants to come and trade on your planet, hauling goods in and out for mutual profit. Plus, once you leave the Sol cartel, you can contract haulers to shift goods for you by posting jobs directly onto the cartel's workboard.
You spend the groats that your planet makes building infrastructure to improve conditions for your populace and enhance the economy - thus making even more money. When you have done enough builds, you can use the 'PROMOTE' command and your planet will promote at the next reset. Promotion means the planet's economy goes up a level; the exchange gets re-rolled which changes all the production and consumption figures and wipes out your existing stocks and deficits.
Assuming you set your planet up correctly, it should make enough money to allow you to build infrastructure using the planet's own money. However, if you find your personal cash is mounting up and your planet is struggling, you can inject some of your own groats into the treasury with 'TRANSFER megagroats', where 'megagroats' is the number of meg you want to transfer, up to 100. 'TRANSFER' can be abbreviated to 'XFER'. Since the Galactic Administration frowns upon large amounts of groats being shifted out of Sol into independent economies, they levy a rather hefty tax of one third on the transfers.
At later ranks, you are allowed to have more than one planet in your system. You can transfer money between two treasuries using 'TRANSFER megagroats planetname' which takes the money out of the planet you are standing on, and puts it into the treasury of the named planet. You have to own both the planets - this isn't a sneaky way of letting you fund a friend or ally.
An alternate way to finance infrastructure builds is to convert four slithy toves to 10 meg, using the command 'TRANSFORM SLITHIES'. The cash is added to your treasury where it can be used to build something useful. You can do this once every two weeks for each of your planets.
Should your planet turn out to be super-successful, you need beware of hoarding your groats instead of using it to better the lot of your citizens. There is a 1 gigagroat limit on the size of planetary treasuries - if your treasury has more than that then the taxman will seize it at reset.
Most planet commands will only work if you are actually on your planet.