How do you draw a ER diagram for an automobile chair industry?

"How" is your work - but this is how to get started:

ER stands to "Entity Relationships". The the real world, "entity" are the things that are to be described - like the "chair" is in a "car". "is in a" is the relationship. Now what things makes up the automobile chair? Then what are these "made of" - another relation, and "who makes them".

The entities are the square boxes - name them carefully. Then draw lines as "relations" - both ways or only one way, and name these also well. Use "Made of" to gather everything that belongs together in the same "thing" / "Entity" - Aggregate. Never show more than 12 entities on the same diagram because that is difficult to understand.

When you have to do things - "Press the lever" this is a "Process" on the entity "lever" - and drawn as a circle.

Now - get on with your diagrams, and be careful not to have too many on the same page - "drill down" and simplify. It is not so important to cover everything as it is important to get it all recorded correctly and in a way that can be communicated and confirmed by others.