If Deluxe includes 5 federal e-files, how to file husbands return (we're married filing separately)?

You will select that you want to start a new return in TurboTax.  To do this, take the following steps:

1. At the very top left-hand side of your screen, select FILE. 
2. Then select NEW TAX RETURN.  
3. You will then be asked if you want to save your current file and TurboTax will bring you through the process of creating a new tax return that can be for your husband.

In the future, when you open TurboTax, you will have the option to choose which tax file you want to work on/access.