null

    #search-input{
      /*use your own image path*/
      background: url(https://img.icons8.com/metro/x/search.png) no-repeat scroll 7px 7px;
      padding-left:30px; /*you may change according to your image width*/
      height:35px /*you may change according to you image height*/
    }

    <input type="text" placeholder="Search..." id="search-input"/>

希望你想在txtbox中有一个背景图像？如果是

回答

<input id="txtSearch" type="text" placeholder="Search..">

<style>

#txtSearch{
background-image: url(https://www.metoffice.gov.uk/binaries/content/gallery/metofficegovuk/hero-images/advice/maps-satellite-images/satellite-image-of-globe.jpg);
}

</style>