ok, here is the edited version.
thank you all for your hints and comments.

in this version, you can see daylight, but i want to change this into a night-scene.
@cat: 1) lets say for now that this weird graffity was the intention of the artist :)
2) I replaced the black lines.
@Akatosh: i changed the perspective to a one-point-perspective.
@ fred: i lightened the water a bit.
thank you all for your help and comments.
i will later edit the water again. now i must shade the picture, but how to do it best? the lamp and that-thing-with-the-number is giving light. the atmosphere must be dark and dangerous.
the 'how' is a great problem to me, especially as i tried it a few times but wasn't content with it.
el1indio
thank you all for your hints and comments.

in this version, you can see daylight, but i want to change this into a night-scene.
@cat: 1) lets say for now that this weird graffity was the intention of the artist :)
2) I replaced the black lines.
@Akatosh: i changed the perspective to a one-point-perspective.
@ fred: i lightened the water a bit.
thank you all for your help and comments.
i will later edit the water again. now i must shade the picture, but how to do it best? the lamp and that-thing-with-the-number is giving light. the atmosphere must be dark and dangerous.
the 'how' is a great problem to me, especially as i tried it a few times but wasn't content with it.
el1indio