eclipse line color background
No correct solution
I don't think it is possible to change the background colour for only comments. There is a 9 year old bug related to this so don't hold your breath waiting for a fix!!
Of course you can: Window > Preferences Then look for Java > Editor > Syntax Coloring In there you can set the style (bold, italic, color, ...) for single-line, multi-line, and javadoc comments (as well as all other syntactic markup).
Edit: Oh sorry, I didn't read the question well enough, as the above only works for foreground coloring.
Changing background colors in Eclipse in general is already answered here.