How or where do you put a sharp note, with respect to the natural key, on the staff?

Question

Is the sharp note put on the same level as the original key? As in, for example, the Key of D is found on the fourth line (from below). Is D# still put on the fourth line, but with the # sign?

Answer 1

I assume you're talking about the treble clef, but the rules are the same for bass, too.
Accidentals (sharps and flats) are placed on the line or space that they "modify," for want of a better word. This can be in the beginning of the staff--the key signature--or at specific points in the composition, if the composer is trying to achieve a certain effect.
Also, the key of "D" doesn't have a sharp on the "D" line: the sharps are on the "F" line and "C" space.

Answer 2

Yes, however if you're doing all D sharps, you'd want to put it at the beginning of the smusic on the far left