How to turn my preteen sim into a teen/adult on Sims FreePlay?

I'm playing Sims FreePlay on my iPhone, and I'm on level 23. I have 2 preteen sims, and I'm trying to turn one of them into a teen/adult (whatever is next). I made a birthday cake, but when I click the sim, it doesn't give me the option to have a birthday. How do I have a birthday for my sim? Please don't comment unless you actually have a legit answer for me.

Dam and i was going to say get him a woman

You need to complete the task for teens or whatever is next