Check this post. Provides an useful example: http://nishantrana.wordpress.com/2010/11/04/adding-my-first-custom-button-in-crm-2011/
A Dynamics CRM Blog
Check this post. Provides an useful example: http://nishantrana.wordpress.com/2010/11/04/adding-my-first-custom-button-in-crm-2011/