How can I improve my skills in Visual basic such as working on objects, strings and integers?

First of all, working with the .NET should be all in obejcts to have all benefits of Obect Orinted Programming.

On the other hand, to improve you skills on programming you should at first read about algorithms and time complexity to improve your work and performance, and you can make a test project and try to use all object properties for strings, date, integer etc...