How do I create a Trigger-based Campaign?

A Trigger email campaign can be created in the following way:
1. Click on the Automate tab.
2. On the left pane, click on Email campaigns.
3. Click on the "Add New Email Campaign" button seen on the right top corner. A popup should open.
4. Enter name of the campaign. Enter a description.
5. Select the template that you want to send for this campaign. Click here:To Add Multiple Templates.
6. In the Criterion select box, choose "On a condition" option.
7. Select the Sender email id that should be used to send campaign emails. The contacts will receive email by this name and email id. If the sender you want is not listed, you can select the custom option which will allow you to enter name and email id.
8. Enter the reply-to email address. If the contacts chooses to reply to the emails received through campaigns, it will be sent to this email id. This can be different from the sender email id.
9. Select one or more criteria for contact selection. You can add any number of criteria that you want. Also you can choose to select contacts that satisfy all the criteria or the ones that satisfy any of the criteria.