You can set the ImageUrl and ExpandedImageUrl properties to the URL of images that will show before the item text in a dropdownlist structure.
@using Trirand.Web.Mvc
@using MVCDemo.Models
@using System.Web.UI.WebControls

<!DOCTYPE html>
<html lang="en-us">
<head>
    <meta charset="utf-8">
    <title>jqTreeView for ASP.NET MVC - Load On Demand via Ajax</title>        
    <!-- jQuery runtime minified -->
    <script src="~/Scripts/jquery-3.0.0.min.js" type="text/javascript"></script>
    <!-- The jqTreeView client-side javascript -->
    <script src="~/Scripts/trirand/jquery.jqComboBox.min.js" type="text/javascript"></script>
    <!-- The jQuery UI theme that will be used by the grid. -->
    <link rel="stylesheet" type="text/css" href="http://code.jquery.com/ui/1.11.4/themes/redmond/jquery-ui.css" />
    <!-- The jQuery UI theme extension jqTreeView needs -->
    <link rel="stylesheet" type="text/css" href="~/Content/themes/ui.jqComboBox.css" />   
</head>
<body>    
    <div>
        @(Html.Trirand().JQTreeView(
                    new JQTreeView
                    {
                        DataUrl = Url.Action("TreeView_TextAndImages_DataRequested"),                    
                        Height = Unit.Pixel(300),
                        Width = Unit.Pixel(300)                    
                    }, "treeview"))             
    </div>
            
    <br />
    <br />
    <div>
          
    </div>
</body>
</html>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using Trirand.Web.Mvc;

namespace MVCDemo.Controllers.Tree
{
    public partial class TreeController : Controller
    {
        public ActionResult TextAndImages()
        {
            return View();
        }

        public JsonResult TreeView_TextAndImages_DataRequested()
        {
            var tree = new JQTreeView();

            List<JQTreeNode> nodes = new List<JQTreeNode>();

            nodes.Add(new LeafNode { Text = "One" });
            nodes.Add(new FolderNode { Text = "Two", Expanded = true });
            nodes.Add(new LeafNode { Text = "Three" });

            var secondNode = nodes.Find(n => n.Text == "Two");

            secondNode.Nodes.Add(new LeafNode { Text = "2.1" });
            secondNode.Nodes.Add(new FolderNode { Text = "2.2", Expanded = true });
            secondNode.Nodes.Add(new LeafNode { Text = "2.3" });

            secondNode.Nodes.Find(n => n.Text == "2.2").Nodes.Add(new LeafNode { Text = "2.2.1" });
            secondNode.Nodes.Find(n => n.Text == "2.2").Nodes.Add(new LeafNode { Text = "2.2.2" });
            secondNode.Nodes.Find(n => n.Text == "2.2").Nodes.Add(new LeafNode { Text = "2.2.4" });
            secondNode.Nodes.Find(n => n.Text == "2.2").Nodes.Add(new LeafNode { Text = "2.2.3" });            

            return tree.DataBind(nodes);
        }

        public class FolderNode : JQTreeNode
        {
            public FolderNode()
            {
                ImageUrl = "/content/images/folder.png";
                ExpandedImageUrl = "/content/images/folder-open.png";
            }                
        }

        public class LeafNode : JQTreeNode
        {
            public LeafNode()
            {
                ImageUrl = "/content/images/document.png";        
            }
        }
    }
}
Switch theme:


Theming is based on the very popular jQuery ThemeRoller standard. This is the same theming mechanism used by jQuery UI and is now a de-facto standard for jQuery based components. The benefits of using ThemeRoller are huge. We can offer a big set of ready to use themes created by professional designers, including Windows-like themes (Redmond), Apple-like theme (Cupertino), etc. In addition to that any jQuery UI controls on the same page will pick the same theme.

Last, but not least, you can always roll your own ThemeRoller theme, using the superb Theme Editor

To use a theme, simply reference 2 Css files in your Html <head> section - the ThemeRoller theme you wish to use, and the jqGrid own ThemeRoller Css file. For example (Redmond theme):

<link rel="stylesheet" type="text/css" media="screen" href="/themes/redmond/jquery-ui-1.8.2.custom.css" />
<link rel="stylesheet" type="text/css" media="screen" href="/themes/ui.jqgrid.css" />