VB App & UML Class Diagram

I am creating a web based application using ASP. I am writing the Data Layer and Buisness Layer in visual basic. I am trying to plan the classes using a UML Class Diagram. I am having real trouble though. Most of the functions the business layer will perform are simple read/writes to the database, there are hardly any associations/generalizations that I can see on the class diagram. Is this normal to have a set of objects that only exist on their own? If so do I just define the attributes and operations for each class and place them on the diagram without any associtations etc?
Also how do I determine the classes, should I have a class for each functional area? For example I need to track jobs that engineers are working on and what equipment they have used. Do I have one class that handles the job functionality and one for the equipment?
Any thoughts

not having any generalizations/specializations is normal (i guess) not having any associations is a bit odd. there should be something connecting these objects. after all if you are defining them they must have some purpose in the situation and connect to something.

in your example you have a jobs that are done by an engineer and that engineer uses tools to do those jobs. those are all connected. i think all three of those would be separate classes. if you have to track it then it is likely a class.