So im making a painting but i dont know what colors to use.......more than two that look good together..?

familiarize yourself with the 12 colour colour wheel (http://www.tigercolor.com/color-lab/color-theory/images/color-wheel-300.gif). Colours that compliment each other are on opposite ends of the wheel(so, the compliment of purple is yellow. You can also put three or more colours together by making triangles, squares, or rectangles on the colour wheel. So, for example, a complementary pair would be red-violet (burgundy), and yellow-green (lime). A complimentary triad (triangle) would be red-violet + yellow-orange + blue-green. A quad compliment (square) would be red-violet + orange + yellow-green + blue, and so on.