You can start from the link:
http://ece.org
1) Print out the application form.
2) Fill it up:
i) Choose course by course evaluation
ii)send one copy of your gpa document to ada even if u wont be taking nbde part 1 recently (you can find ADA address in their website)
3) Send the documents along with the photocopies of each document.
The documents needed are
1. your class 10 and 12 marksheets
2. your marksheets of all 4 years for undergraduation and postgraduation if any.
3. transcripts of marks and study hours
Just send them everything you have. You will receive your GPA and all the original certificates in about a month. If u have any questions, you can always call ECE.