I don't think Basic has a way to do that through the program. 

You'd have to print to PDF (or run it through your scanner and save to pdf) then use a 3rd party program to password protect and attach to email like any other file you'd send in email.

I use Bullzip for password protecting files for Email.

If you are preparing your returns with ProConnect simply use Intuit Link.

1.  Navigate to the client. 
2. Click View Return
3. Look towards the top and click File Return
4. On the left side under Print click View/Print Return PDF
5. Click on Share PDF via Link

Basic doesn't do it.  You do have to do your own thing.  Personally, I use Adobe for that stuff.