You can make changes in the example given in MathWorks documentation page to use different data which has different number of samples.
tbl = table(Horsepower,Weight,MPG);
N = size(tbl,1);
Instead of using carsmall dataset you can load your own dataset.
cvp = cvpartition(N,'Holdout',0.1);
idxTrn = training(cvp);
idxTest = test(cvp);
You can partition your own data into training data and the testing data using cvpartition(N,’HoldOut’,p) by setting p to get p*N number of test samples.
Also ObservedValuevariable in the ans table is the actual target value for the test data and the PredictedValue variable in the ans table is the predicted value for the test data.