Select either "Any of" or "All of" from the top combo box. To make one of conditions apply to the rule, select "Any of". To make all of them apply select "All of". For example: if one condition contains "new" in ticket title and the other contain "new" in the ticket body, the "Any of" option means that it's enough that the word "new" appears in either of them for the rule to apply, whereas the "All of" option means that the word "new" has to appear in both for the rule to apply.
If you have conditions, click on "Add condition…" and select the desired condition.
To add another condition (you can add as many as you'd like) click on the "Add condition…" link below the current condition.
Click on "Add action…". Select the action you want to be automated from the combo box.
In the bottom combo box, select either "Continue processing rules" or "Stop processing rules".