1. On the Profile tab, make sure you check the box for SELECT FOR E-FILE;
2. On the Check Return tab, ensure all the Critical Diagnostics are cleared;
3. On the File Return tab, check the box SELECT TAX RETURN(S) TO E-FILE and click on the E-file button.  If these options are greyed out, that's because you haven't yet cleared all the critical diagnostics and you will see a red exclamation mark under the DIAGNOSTIC column.

This is the same routine for all types of return.