You can use a NameValuePair list to put multiple parameters to your POST request, as in :
try {
HttpPost httpPost = new HttpPost("url");
List<NameValuePair> parameters = new ArrayList<NameValuePair>(2);
parameters.add(new BasicNameValuePair("login", "trout"));
parameters.add(new BasicNameValuePair("password", "salmon"));
httpPost.setEntity(new UrlEncodedFormEntity(parameters, "UTF-8"));
HttpClient httpClient = new DefaultHttpClient();
HttpResponse httpResponse = httpClient.execute(httpPost);
String response = EntityUtils.toString(httpResponse.getEntity(), "UTF-8");
} catch (UnsupportedEncodingException e) {
} catch (ClientProtocolException e) {
} catch (IOException e) {
}