Using Okhttp to get a json file but need to add a username and password

I am trying to log into server to receive a json file back. But the server needs a useame and pass word. I don't know how to add that into my build. I looked at a lot of sources but I caot figure it out what to add to my builder. Thank you very much for any help

Here is my OkhttpHandeler code

public class OkHttpHandler extends AsyncTask<String, Void, String> {

OkHttpClient client = new OkHttpClient();
Response response;
Request request;
private final String apUrl = "http://xxxxxxxx.xxxxxx.com/api/1.0/promotions";
String output;
String picture;
//JSon Data
String jsonData;
JSONObject jsonObject;
JSONArray jsonArray;



@Override
protected String doInBackground(String... params) {


    RequestBody formbody = new FormBody.Builder()
            .add("useame", "admin")
            .add("password", "admin")
            .build();

    //Request.Builder builder = new Request.Builder();
    //builder.url(params[0]);

    request = new Request.Builder()
            .url(apUrl)
            .post(formbody)
            .build();


    //request = builder.build();

    try {
        response = client.newCall(request).execute();
        Log.d("Respones:", response.body().string());
        output = response.body().string();

        jsonData = output;

        try {
            jsonObject = new JSONObject(jsonData);
            jsonArray = jsonObject.getJSONArray("");
        } catch (JSONException e) {
            e.printStackTrace();
        }

        try {
            JSONObject object = jsonArray.getJSONObject(0);

            picture = object.getString("picture");
        } catch (JSONException e) {
            e.printStackTrace();
        }
        //retu response.body().bytes();
        retu picture;

    }catch (Exception e){
        e.printStackTrace();
    }
    retu null;
}
}