Econmetrics Help - Run a gregression of C on Y and N and estimate the regression coefficients.?

I don't get it, are you required to do it BY HAND? If not, try to do this with any statistical software package: once you know the right commands it'll take you a couple of minutes. But as a general comment, whatever coefficients you get, they cannot be considered as consistent, since your sample is not representative. If you need some theoretical background so that you understand what's going on, check out introductory Wooldridge, it gives (in my opinion) an excellent intuitive and well-presented exposition of the issues you have described.