Triggers in Continua are used to automatically queue (a.k.a trigger) the Configuration they belong to when a certain event happens. These "events" are grouped into three categories.
Each of these trigger types have their own fields and values to be set, the explanation of each field is described in their respective pages of this wiki. Regardless of the trigger type selected, they all share a set of common fields which are described below.
The trigger isn't operational unless this option is selected.
When the trigger is executed and the Configuration is queued, the build needs to decided what to do with the Repositories attached to the Configuration. In the case of a Repository Trigger, the triggering Repository is assumed to be in a working state since it just triggered the build. However, the same can't be said for all non-triggering repositories of which there could be many. In the case of Time Triggers and the Project Completion Trigger, all repositories are non-triggering repositories. For Repository Trigger, the non-triggering repositories are all those repositories other than the one that triggered the build. When the force repository check option is set, all non-triggering repositories are check to see if they're in an error state. If they're in an error state, an attempt will be made to fix them. If they're still in an error state then the build won't start and you'll see an entry in the Event Log with the details.
There are times however when you might not care if the repository is in an error state. When you setup a repository in Continua, it immediately copies your repository into a repository cache directory located in the Continua Share directory you setup when installing Continua. Continua makes sure that the cache is always up to date by polling your repository every now and then (specified when you create a Repository). If Continua can't contact your repository then it's marked as errored and as a result the cached version of your repository may not contain the latest changes. By not selecting the force repository check option, you're telling the trigger to not check the repositories (and possibly not get the latest changes from it) and instead use the latest cached version.
This is the part where you select the trigger type explained above. (Repository, Time trigger, etc..)
The variables drop down will contain a list of all Configuration variables you've created. It gives you the ability to change a variable's value when the trigger executes the Configuration. By clicking the plus icon to the right hand side of the input field, you can set the value of any amount of variables you like.