28 years old, how do I claim myself as a dependent

[IreneS]

You don't claim yourself as a dependent (but neither do your parents). 

As you go through the interview, in the Personal Info section TurboTax will ask you if someone else can claim you as a dependent.  Answer No.

To check your entries, click the My Info link in the black bar at the left of your screen.  In the first section (under your name) you should see the entry "Can’t be claimed by someone else."  If you don't see this click Edit next to your name and change it under question #3.