Need your opinions on UI related issues

The major part of software source codes, which I have written are mostly for background processing and I have worked very little in UI designing. Moreover, I do not have the bent of mind, which is required for the creativitiy to think of a good UI. Therefore, I seek your opinions on the following. Some of these questions may look too simple to most of you, but, for me, they are important.

Suppose a Windows form shows graph. There are x and y values. They are plotted along x and y axes. The points are shown by small circles and they are joined by a curve.

Please let me know what you think will be the best colors for the following: -

1. The small circles representing data points.
2. The curve, which joins the points.
3. The lines, which represents x and y axes.
4. Labels displaying what the axes stand for.
5. Some other texts to give more information on the graph.
6. Background