If your current certification is in NY State childhood education (grades 1-6), you are eligible to work towards an additional certification in Early Childhood Education (B-2). More information is available on the NYSED website.
The NYS Education Department allows already certified teachers to apply for additional certificates on their own. You may view the requirements on the NYSED Search Certification Requirements site.
To add Early Childhood B-2 (once you hold Childhood Ed 1-6) and/or Students with Disabilities (SWD) B-2 (if you also hold SWD 1-6) you will need to re-apply to the NYSED online and mail them your transcript(s). You are not applying for extensions, but rather stand-alone certificates in Early Childhood Education and/or Students with Disabilities B-2.
The NYSED will want to see at least 6 credits that focus exclusively on Early Childhood, which you may have already completed as part of your program. If you have, go back to the TEACH Online system, apply for the additional Initial Certificate(s) (or Professional only if you already hold Professional in another area) online following the instructions on the website.