Find out the basics of Harvard referencing from Cite them right online including:
If you are a 3rd or 4th year student and have used the old DMU Harvard until now, check with your tutors what version they expect you to use.
Switching between the two versions is easy if you simply follow the formula for the type of resource you need to reference. The most visible difference between old and new style DMU Harvard is that author's surnames in the Reference List are NOT capitalised in the new Harvard.
The key point is to be consistent (don't mix and match different versions in the same assignment!).
This is a link to the old DMU online Harvard guide if you need to continue using it.