debuging a plugin

hi  i am trying to debug a plugin .
my site is running on my local host using web matrix
when i am attaching the debug process i cany find my plugin pdb ,
any suggestions ?

what is the best way to debug ?

WebMatrix has limited debugging ability.  Use Visual Studio.
(Also, I assume you have the source code version of nopCommerce??)

What are the steps that i need to do ?