how to set break points in jdb

I need to debug an application with jdb. I am new to this tool. when ever I try to do anything I get an error, for example, if I do : "jbd MyClass"

then try

>classes

I get.

Command 'classes' is not valid until the VM is started with the 'run' command

I dont want to run the class before setting the beak points.

can any one advice me please ?

[393 byte] By [M-Aa] at [2007-10-3 4:50:09]