Registration of charitable trust with charity commissioner

I want to register a Trust with the Charity Commissioner. The Charitable Trust does have a PAN Card. Please let me know the procedure for the same. Which form is to be filled and what documents are to be filed?

Also, if the Trust wants to go for FCRA Registration, is registration u/s 12A and 80G a pre-requisite or can that be done even after FCRA Regn?