How do you money on mini planet on facebook?

To EARN money, You:
1.Clean Neighbor's rooms
2.Play Games
3. Have a sale and sell your junk.
4. Manage your store so you get money.
5. Pay for it with a credit card, gift card, of your mobile phone by going to "currency"

There are many more ways, but those are the basics.

To SPEND money you:
1: Buy stuff in the store
2. Participate in the lottery
3. Go to the events and buy stuff from peopl's sales (watch out, they may scam you.)
4. Buy rooms for your pad and redesign them with the new furniture you bought from the store.
Again, those are the basics. You can find your own ways of spending money.

I hope this helps. Have fun with miniplanet! :D