'there/in there/over there'

Dear Teachers and Moderators

I found it difficult to make a clear distinction between 'there' and 'in there', 'there' and 'over there' as well.

1. I'll go there/I'll go in there

2. He is there/He is over there

3. People here are kind/People in here are kind (by the way)

Thanks in advance.

Thanks for helping me!!

'Look at the girl sitting over ther!'

'I'm gonna go in there'(pointting at a door)

Are they correct?

Thank you, pieanne.

English Forum is a splendid site for beginner! I really need more practices and to be correct.

Thanks again.