All the authorities notified under Section 51, are required to register on GST portal as TDS (Tax Deduction at Source) Deductors. They are also required to deposit tax deducted with Government.
A. Standard Operating Procedures (SOPs) on TDS issued by GST Council
http://cbic.gov.in/resources//htdocs-cbec/gst/28092018_SOP_ON_TDS.pdf;jsessionid=A7960EC5012618B2FE26595A7D54AC18
B. Registration on GST Portal
User Manual
https://tutorial.gst.gov.in/userguide/registration/index.htm#t=Tax_Deductor.htm
Frequently Asked Question (FAQ)
https://tutorial.gst.gov.in/userguide/registration/index.htm#t=Registration_as_Tax_Deductor_or_Tax_Collector.htm
Computer Based Tutorial (CBT)
https://www.gst.gov.in/help/video/tdsparta and https://www.gst.gov.in/help/video/tdspartb
Webinar
C. Payment on GST Portal
Guidelines of Government regarding payment by TDS Authorities
https://bit.ly/2xjRrHM
(Department of Revenue, Government of India, Circular No. 65/39/2018-DOR dated 14/09/2018)
User Manual (FAQ)
https://www.gst.gov.in/help/payments
Frequently Asked Question (FAQ)
https://www.gst.gov.in/help/payments
Computer Based Tutorial (CBT)
https://tutorial.gst.gov.in/cbt/payments/gstpayments/index.html
Webinar