Http http = new Http();
HttpRequest req = new HttpRequest();
req.setHeader('Content-Type','application/x-www-form-urlencoded');
req.setMethod('POST');

String body=  getAccountDetail(accountId);
req.setBody(body);

body='ocid='+value1+'&o='+v1 & v2
Ex: body='ocid='+value1+'&o='+'Dun & Bradstreet'