This is how you might draw your sine wave.
The header files had a getmaxx() and getmaxy() for the screen, but you can plug in the numbers that you want, directly, if you don't have these functions.
Code:
#define pi 3.14159265
ypos = getmaxy() /2;
crest = getmaxy() /4;
width = getmaxx();
for (i=0; i<width; i++)
{
swing=crest * sin(10*pi*i/width);
putpixel(i, ypos+swing, RED);
putpixel(i, ypos-swing, BLUE);
}
I'm curious if you can't put in a getchar() right after that is drawn, and then while the screen is being "held" in place, hold down the Ctrl key and press the PrtScrn (print screen) key.
Which should put your screen into your system's memory. Then just open up Paint (Start >> Show All Programs >> Accessories >> Paint), and paste the sine wave, right into Paint.
Now save the image as a BMP file, in Paint.
I do this with regular screen's to post up screenshots, so it should work for you, as well.