You need to begin by studying the difference between active and passive voice. Here is an example.
Active voice. Mary cooked dinner.
Passive voice. Dinner was cooked (by Mary).
The best way to do this is to sit down and look at a good grammar book. If you don't have one, you could search the forum here for the terms 'passive' or 'passive voi
The car is washed. When we say this, we are usually mean that the car is clean. ie the state. Of scourse, someone did some work, but we don't really care about that.
The car has been washed. Here, we are thinking that someone has washed it. ie an action.
Do you have any questions about this? If not, we can