How to use the tar -I option

Question

I'm trying to tar up all the *.class files only on a Solaris box under a certain directory. Reading the man pages for tar made it seem like the -I option is what I wanted. This is what I've tried from the dir in question:

find . -name "*.class" >> ~/includes.txt
tar cvf ~/classfiles.tar -I ~/includes.txt

From that I get:

tar: Removing leading `/' from member names
/home/myhomedir/includes.txt

And the ~/classfiles.tar files is garbage.

I don't have write permission on the dir where the *.class files are so I need to have the tar written to my home dir. Could someone tell me where I have gone wrong? What tar magic should I use?