1. Login as a Manager,
Manage - Auto-Mails
Open Mail Settings tab. Where you can see red rectangles please fill this with you gmail account data.
User Name - it's your e-mail address, (f.e firstname.lastname@example.org)
Password - password which you are using to login to your gmail account
Display name - Your hostel name
From e-mail - it's your e-mail address,
After all you have to save it, and chceck by Test Email if this settings are correct.
Please let me know if this soluton helped you.