My principal is resinging from the firm...wat to do now??

Hello guys.....actually my principal is resigning from the firm and i want to stick with the firm and want to continue my balance period of articleship under other partner of the same firm......so my ques. is

1) wat form or forms i have to fill

2) application is necessary to be sent first to the institute and if yes...wat content i mean roughly idea wat to  write in the application.

pls answer this short question i'll be very glad and thankful to you guys....:))))