<div class="form-control">
    <div class="input-group">
     <span class="input-group-addon">
        <input type="text" id = "fromuser"></input>

    <select id="combobox">
        <option value="">Select one...</option>
        <option value="abc">abc</option>
        <option value="cde">cde</option>
        <option value="xyz">xyz</option>
      </select>
      </span>
    </div>
</div>