Learn to make a proper comment. // is right, / just causes us more work to try to get the code to compile.
setPixel(Position[i], red, green, blue);
replace that with the line @ PaulRB posted. Or find the setPixel function that is missing.
showStrip' was not declared in this scope
Shouldn't that be FastLED.show();? Or is there supposed to be a showStrip function (that is missing)?
setAll(0, 0, 0);
Another missing function? You might use the fillSolid library function:
fill_solid (struct CRGB *leds, int numToFill, const struct CRGB &color);