How to express the idea of being somewhere


So I've been searching the internet and I can't find my answers because all it
says is the N5 imasu/arimasu I don't think it's right.

So the context is like "imagine, you are in a place where blah blah"

I can't find any JP lessons in the internet that covers this certain kind of
existence other than imasu and arimasu. Pls help thanks!

