I am trying to find the standard curve for my lab data but I am having trouble finding out what my x and y values are.

I am trying to find the standard curve for my lab data but I am having trouble finding out what my x and y values are. the x value is concentration of dopachrome (mM) while the absorbance is what we got using the spectrometer. we used 8 tubes and put dopachrome in tubes 1, 3, 5, and 7 while putting buffer in 2,4,6, and 8. i have all the absorbances for tubes 1-8 for all the dilutions, but I'm trying to figure out how to find the y=mx+b equation and turn it into the standard curve so i can answer the question at any amount of concentration given.