SLAs allow you to define rules which set when a ticket should be marked as overdue or in breach of a service level agreement. When tickets are submitted they can optionally be assigned to an SLA which will ensure that responses are provided in accordance with your defined rules.
To create a new SLA, click on the SLA link in the Admin navigation, just below the Schedules link. Click 'Add New SLA', type in a name for the SLA, select the schedule it will relate to, and then type in the number of minutes within which you expect tickets with this SLA to receive a reply, and the number of minutes within which you expect them to have a resolution, then click 'Save SLA'.
To edit an SLA, either click its name, or the pencil icon. To delete one, click the red 'X' next to the pencil.