I appreciate your help, thank you!
It didn't work. I guess I have a mistake.
Txy values seem as a Nan+Nani
It is also good to know Fs can be 1 Hz. I also have data with 1 Hz
Y = B1(1:50001,5:5);
X = B1(1:50001,6:6);
[Txy,F] = tfestimate(X,Y,50001,,,Fs) ;
% to plot the magnitude plot you need to take the magnitude