How to create overlay contour map?

Hi

I'm trying to create an overlay contour plot of 9 reaction time (RT) data points. Each data point corresponds to a specific location on a 3x3 matrix (e.g., RT1 = location 1, RT2 = location 2, RT3 = location 3, and so on). This is shown below:

123

456

789

Original RT data points were adjusted (average RT of all 9 points was calculated and each RT point was subtracted from this mean) - and are provided below:

27.51 (location 1)

48.69 (location 2)

-26.53 (location 3)

2.36 (location 4)

97.06 (location 5)

31.99 (location 6)

-111.64 (location 7)

-11.34 (location 8)

-58.06444444 (location 9)

I wish to create an overlay contour plot to superimpose over an image (considering the difference in reaction time speed to various locations). The images over which the contour plot will be superimposed are 600 x 600 pixels. Hence, it would be ideal if the colours in the contour plot were somewhat transparent.I have tried using two codes I found online but I was unable to incorporate my own data into the formula as I have no experience or knowledge of matlab. So I would be very grateful if anyone could point me in the right direction and be able to explain (in simple terms) what I need to do.

Thank you.