you have the parity check matrix H. H is devided into 6 sub matrices A,B,C,D,E and T such as T should be a triangular matrix. and also if the matrix H is not that form (T is not a triangular matrix) so by changing the columns and the ligns (permutations) you will get this form of the matrix H. When you obtain these matrices, you know the codeword is composed by the systematix and the parity bits and the vector of parity bits is also composed into 2 vectors p1 and p2 and in the article of Ridcharson and Urbankie you will see the formulas to obtain the vector p1 and p2.