do you have a mail program installed on your server?
if you execute on the command line:
echo Testing 123 | mail -s test firstname.lastname@example.org
replacing your email address, do you get the email?
Look in your commands.cfg file. There is a default command called notify-host-by-email and one called notify-service-by-email. Make sure they are there. If not, look in the docs for an example of it.
In your contact definitions, make sure for your name that you have yourself as a contact with notifications enabled and pointed to the correct commands. Here is an example
#contactgroups Server Admins
Then make sure that your services and hosts (or a parent template) have
That will email you anytime a hsot goes down, recovers, starts/stops flapping and enters scheduled downtime and whenever a service is in critical, warning or recovers.
Study the docs a little bit and you will see with templeting and inheritance, there are a billion and a half ways of applying this, but that is the basics of it. Have a contact with an email address and contact options, have a host or service with the contact as a contact with notification criteria set.