You'll fit the cross-covariance curve the same way you fit a semivariogram. You'll see empirical covariances (blue crosses), and you need to manipulate the parameters (range, nugget, sill, lag size, etc) to get the curve to go through the crosses as best you can. The first thing to try should be the "Optimize Model" button. Hopefully that will be able to fit everything automatically, though you may want to do some manual tweaking from there.
Also, if you're doing external research, the cross-covariance curve is often called a "covariogram."