how to find training or testing data from a matrix????

suppose

A = [ 6 3 11 7  8 5 1 2 4 9 10;
     11 5  6 3 10 8 4 7 2 9  1;
     10 8 11 6  7 3 9 5 4 1  2]

In this matrix we want to divide in training or testing data but a condition applies that only 3 & 6 will be as test data & the other is as training data set then what condition or method being applied???answer me