Our point of sale software talks to Microsoft Office which is in my experience a terrific program to use but in practice does require a lot of learning.
So if you feel you need to learn more to get a grip with its functions. Microsoft has released a training resourses and a roadmap here for it.
You will find these top-quality and highly instructional.
If you do not have Microsoft Office and do not want to get it, you can always with our system use the free Open Office system which is also extremely powerful.