Strictly speaking, VB supports inheritance. There are three kinds of inheritance: implementation inheritance, interface inheritance, and visual inheritance, because vb6 supports interface inheritance.
Code reuse is just like comprehension. You will understand when you reach the realm. It is definitely not a few sentences or a few examples.
The only way is to practice. As long as you really regret "Why wasn't this part of the code organized like this at the time", you will always keep the organization of the code in mind, otherwise most will give up due to external pressure such as progress.