Starting a project involving Access database

[o2f2]

So I'm attempting this project, but have no idea where or how to start. What I want it to do:

A program for a mail-order company that enables a clerk to enter each catalog number for items the customer wants to order. After entering catalog number, the program looks up the item's price, description, and quantity available. When the clerk enters the quantity desired, the program verifies that the quantity is actually available and calculates the total price for that item and added to the order total. The information for the total order will be displayed on a separate sheet.

Basically, I need help determining how to do the dataset part. I do not have Access but am looking at creating a dataset in VB. But, I have all the information written as code also.

Any advice would be appreciated...I am so lost!!

Thanks!