Some MDS codes over dihedral groups

In this paper,we show some $[2n,2n-2,3]$ and $[2n,2n-3,4]$ MDS codes over dihedral codes $F_q{D}_{2n}$,in the case $n$ is odd and char$F_q$$\nmid$$\mid G\mid$ and $F_q$ contains primitive root of exponent $\mid G\mid$ i.e $F_q$ is the splitting field of $G$.Before that,we will give the Wedderburn decomposition and specific forms of linear primitive idempotents of $F_q{D}_{2n}$ under the above conditions.The MDS codes we construct are obtained by its Wedderburn decomposition and linear primitive idempotents.