Here are the information you would require:
1. yes, you can send it by registered post, and you do not need to go in person to file an appeal or even during the hearing. Read this:
appellant presence during 1st or 2nd Appeal not nessessary.
& this:
http://www.rtiindia.org/forum/1623-post4.html
2. Here is all what you need to do for the First Appeal:
http://www.rtiindia.org/forum/1820-post2.html