function OnGUI () {    
    GUILayout.BeginHorizontal ("box");

    GUILayout.Button ("I'm the first button");
    GUILayout.Button ("I'm to the right");
    
    // End the horizontal group we began above
    GUILayout.EndHorizontal ();
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void OnGUI() {
        GUILayout.BeginHorizontal("box");
        GUILayout.Button("I'm the first button");
        GUILayout.Button("I'm to the right");
        GUILayout.EndHorizontal();
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def OnGUI():
        GUILayout.BeginHorizontal('box')
        GUILayout.Button('I\'m the first button')
        GUILayout.Button('I\'m to the right')
        GUILayout.EndHorizontal()