addMethod in Validation plugin

addMethod in Validation plugin

I have one selector and one input box contains div id countryName and name. Now I am using validation plugin to validate. I want to do some thins if selector value none then alert will appear on click please select country on click submit. And in case of input box if input box contains . $ % then alert will appear special character not allowed on submit click. I understood I need to addmethod   but unable to understand how to create the method can any please help me with this?
Thanks