How can I transfer these equations into MATLAB codes?

I am new with MatLab,and I want to know how can I transfer the following vibration equations into MatLab codes.

X''=-(M^-1)*K--(M^-1)*D*X'+(M^-1)*B*u
Sys=ss(A,B,C,D)

And M,K,D,B are matrix that I already get.

Thank you.

[Star Strider]

Please explain what you want to do with the -- in this:

X''=-(M^-1)*K--(M^-1)*D*X'+(M^-1)*B*u

[Yuxing Zhang]

Thank you for asking, now I input the four matrix values and want to know if there's a code that I can use to relate the x'' with x'=Ax+Bu and y=Cx. so that I can get matrix A,B,C,D.