If you have added your own custom fields to an event registration, you will need to each one to the notification email template. This means that when you get a notification email that someone has signed up, these custom fields you entered will also show up.
Go to components>event registration>event administration and click on the event you want to edit.Go all the way down to the bottom of the page and the last text area box. It is called 'notification email.'
Click inside this text box with the mouse.
Check the box on the right of this text area box that says "include fields label when inserting"
Now click the dropdown menu above this checkbox that says "select."
Find the field you want to add from this dropdown menu and click it. It will now show up inside the notification email template text box. Add all the fields you want to show up there by selecting one at a time.
You will probably need to use the firefox browser to see all the fields you made in that dropdown menu. In IE, oftentimes they are white and invisible.