When first installed, AltaMail shows a more basic send email screen. To see the advanced options, tap on the "..." button at the top of the new email screen.

The advanced options include "CC", "BCC", choosing the "From" address/alias and adding/editing attachments. You will also thee the action menu which allows you to choose a time to "Send later", add a read receipt, set the priority and choose a signature. You can also edit the email as plain text instead of formatted text.