i don't under stand what this is supposed to mean. Is it just vocabulary practice?
It means 'why can't you place yourself', perhaps a school exercise where they have to choose to place themselves in categories and so some asks that question. Although it is a peculiar sentence :)
This is meaningless in English.
Is it wrong without "selv"?
Why not "sig"?
Because "sig" is only third person: himself/herself/itself/themselves.
Strange. It's not a common phrase, that's why it's odd. I'm not a linguist but it seems 'place' is the noun when it should be an adjective. Why can't you place yourself in the seat. Even then it's not common but it would acceptable.
I think when when you say adjective you mean verb.
And, what distinguishes "placere" from "stille", I wonder?