A family of Microsoft relational database management systems designed for ease of use.
Morgan,
It depends on why the task is delayed. Is it because it is taking more work to accomplish than originally plannedm is it because the resource(s) working on it were temporarily pulled off to another task, or perhaps the whole task is slipped for various reasons. In the first case, you can simply drag the end of the Gantt Bar to the new scheduled finish date. In the second case, you can use the split task icon (Task/Schedule group/split bar icon) to create a delay (i.e. split) in the task bar. If the whole task is delayed you can grab the center of the Gantt Bar and move it. In the first two cases, the duration will expand in response to the delay, assuming the task has already started.
Now for the bonus round. Once you set up a schedule with all the tasks, links and resources to work the tasks, you should set a baseline (Project/Schedule group/Set Baseline icon). That will take a snapshot of the Start, Finish, Cost, Duration, and other normal fields such that you can view the variance either visually (Tracking Gantt) or via one or more of the variance fields (e.g. Duration Variance, Start Variance, etc.)
And since you are new to Project, do not confuse duration and work. Duration is simply a span of working time between the task's start date and finish date. Duration accomplishes nothing. Work on the other hand is the estimated amount of effort to actually perform/complete the task. The Percent Complete field measures duration while the Percent Work Complete measures effort. If a single resource is assigned full time to a task, then duration and work will be equal, but normally that is not the case.
Hope this helps.
John