Tell me How to use Gaussian process regression with my data

Hello. I am a new beginner of MATLAB and I was told to do regression analysis with Gaussian process(GP) regression. I found GP code for MATLAB on the below site http://www.gaussianprocess.org/gpml/code/matlab/doc/ However, I have no idea how to apply it. For example, the relationship between y and x1,x2,x3,x4 is y=a1x1+a2x2+a3x3+a4x4. x1=[0,1,2...,10]' x2=[1,2,3...,11]' x3=[2,3,4...,12]', x4=[3,4,5...,13]' y=[6,10,...,46] In this variables x1,..,x4 and obeservation y, how can I apply GP?? Any advice would be greatly appreciated!

[zhan sui]

I am a student, I see the post you made, I encountered the same problem in Gaussian process regression study,if you have solve the problem, could you help me?