You can probably start on page 9 and start reading from there onwards. Each step tells you what to do.
The Auto Attendant (AA) section starts on page 25 (step 10 B. i): "But what if you wanted to use your cellphone to make free calls using Freephoneline or any other
service that is configured on your ATA using regular cellular airtime (and not cellular data) by
simply dialing your Freephoneline phone number?"
The AA section continues on page 26.
The Auto Attendant section then jumps to pages 30 and 31 (for enabling AA and using a PIN).
And there's a follow up question covered on pages 51 and 52 for how to enter in a contact on an iPhone or Android smartphone using a pause (or comma).
On an iPhone the entry would look like (519)123-4567,21234#,9051234567
(519)123-4567 is your FPL number (your FPL phone number because an access number to your ATA, basically)
, is a pause (to ensure the call completes first before entering in other digits)
2 is to make an outgoing call using Auto Attendant
1234 is your PIN
# is the pound key (to finish entering your pin)
, is another pause
9051234567 is the number you actually want to dial