How can i change the menu text color

How can i change the menu text color
so what file can i edit?

Grab the Firefox "Web Developer" extension and, of course, firefox if you don't already use it. It is a huge help. Try out the CSS menu option "View Style Information". You can then click on the element in question and it will tell you the style information and the file.

I am guessing that by menu, you mean the catalog categories list. If so, then the file is catalog\template\default\css\default.css

Also, try searching the forum. Advanced search on css should pick up some interesting discussions on how to modify this.