right click on the sql agent job, select properties, go to notifications. Set up an agent with the appropriate email, then select an email address, select an agent, and then when the job fails. Click OK and you should be good to go. note that this solution will only take care of one sql server agent task (each sub-plan of the service plan). therefore, you will need to set up a notification for each part of the subplan (if you have several subplans).
How to create an operator.