You can set a rule to automatically label tickets with a certain title (keyword) to a certain label.
You first need to create the label (tag) to use.
To create a label:
1. Click the label button
2. Click co "Create label"
Once you have labels, you can use the rule.
To create the rule:
Use the condition "Ticket Title" and fill in the keyword. Select the "Add label" action and choose the label from the drop down.