Earn Simoleons by completing Career Events with your Sim. Then use Simoleons to buy cool stuff for your Sim in Create a Sim or in the Buy/Build menu.
You can also buy Simoleons using SimCash.
You earn some SimCash by levelling up, but the best way to get SimCash is to buy it from the Shop.
Use SimCash to buy premium items for your Sim in Create a Sim or in the Buy/Build menu.
What can you do with all those Simoleons and SimCash? Buy cool stuff, of course!
Boosts let you refill your Sims' needs.
Here you can buy Cupcakes.
You can also buy Boosts directly from your Inventory. Make sure you select the right Sim and then follow these steps:
Buy new clothes and accessories in Create a Sim.
Simmers can restore their missing purchases, furniture, and Create a Sim items.
Click on the Restore Purchases button in the Settings menu to restore items.