This book addresses the options that teachers have for registering their students. Read the Online Registration book if you have not done so. It has information about creating a science fair application. There are a number of ways to do this that differ depending upon the grade/division of the student.
This book covers everything you need to know about registering for the Mercer Science and Engineering Fair. You can access the main science fair page (presented when you log in) using Home / Registration from the main menu on each page.