my friend is in lawton ok and has been recently been accused of having illegal substance on the backside of a stamp i mailed to him. Can someone tell me how i can get involved or who to contact

That is a very serious charge and before you "get involved" any further, maybe you should get some legal advice. If he was accused of something you sent, you might put yourself in a position to defend yourself. Forget about saying, "you had nothing to do with it", all the inmates there are innocent, too