How do I complete an application? New applicants can apply online to be a substitute teacher or substitute instructional assistant through the FCPS Instructional Talent Gateway.Explain who you are and your reason for writing, including how you found out about the position. This guide describes how to apply for jobs using the Career Page web site. The process consists of the following steps: Learn what to include in your cover letter for a teaching position when you have no experience and use our template and examples as a guide. Ashley Starkston is applying for a high school choir teacher position with Fairfax County Public Schools.