Hi vfam2player. You upgrade career rooms on your iOS device by:

• Tapping the "Store" button.
• Next, tap the "Career" category.
• After that, tap the upgrade item you would like to purchase (assuming it's unlocked and your peeps have enough money to pay for it).
• Lastly, tap the "Buy" button.

You will then be taken back to the main scene, your new purchase will self-install and all of your little family members will run to see it and celebrate the upgrade. They love getting new things!

You really should check out: Helpful VF2 iOS Tips & Answers and [SPOILERS] Fires, leaks, clogs and more!. It will help you with many things you're wondering about. Good luck and enjoy your little family!