Do I add my wifes income in the income section while logged in as myself? Or does she login and fill her info out under her account?

If you are filing a joint return, than yes, you would just add your wife and her income to your return in your TurboTax account. She does not have to log in to enter it. You will enter everything in one place. All of your income, all of your deductions, etc. etc.

If you selected to file your tax return as Married Filing Jointly in the My Info section of the online editions, then all income from all sources for both you and your spouse are entered on only ONE tax return.

In the TurboTax program section of Wages & Income the program will ask for the owner of the income or the Form by Name.  Go back to the W-2 section and click on the button to Add another W-2.  If the program does not aske for the Name then you Did Not select to file the return Jointly.  Go back to the My Info section and edit your personal information to include your spouse on the tax return.