To get started with the ‘Invite Friends’ option you will have to click on the option which says ‘Invite them now’ available in the sidebar under the ‘Get Connected’ section.
Next you would be shown with a box to enter the Email addresses whom you would like to Invite along with any optional message which you would like to add. Next click on the invite button and proceed.
Apart to this normal way of inviting friends through manual emails, you can also import email addresses from almost any online email service to invite your friends. This includes major services like Windows Live Hotmail, AOL, Gmail, Yahoo Mail etc. For this you will have to click on the logo of any of these services and facebook would show you a small window to enter the logins to these services in order to download all the contacts from the selected service and then upload to facebook.com after the importing emails process.
Next you will be asked to login to that emailing service and also allow facebook to access your contacts. If facebook cannot directly import the contacts you will be asked to download and then upload the same to the service.
Finally a list of all the Friends & Family would be listed along with the full name and email address following which you need to click on the ‘Add to Invite’ and a invitation will be sent on your behalf to all your friends at a time.