You can bind the control to a datasource using both declarative and programmatic datasources through the DataSourceID or the DataSource properties. DataTextField and DataValueField define the Text and Value properties for the respective Item - mapping the respective columns from the datasource to the text/value properties of the item.

You can also just add items to the Items collection directly with code. Adding items to the control is easy - just create a new JQListItem instance for each item, set its Text property (optionally Value and other settings) and add it to the Items collection of the control.
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="default.aspx.cs" Inherits="JQSuiteASPNETExample.examples.multiselect.loaddatabase._default1" %>
<%@ Register Assembly="Trirand.Web" TagPrefix="trirand" Namespace="Trirand.Web.UI.WebControls" %>

<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8">
    <title>jqAutoComplete for ASP.NET WebForms - Load From DataBase</title>
    <!-- The jQuery UI theme that will be used by the combobox  -->
    <link rel="stylesheet" type="text/css" href="" />    
    <!-- The jQuery UI theme extension the autocomplete needs -->
    <link rel="stylesheet" type="text/css" href="/themes/ui.jqmultiselect.css" />
    <!-- jQuery runtime minified -->
    <script type="text/javascript" src="/js/jquery-3.2.1.min.js"></script>
    <!-- The jqAutoComplete client-side javascript -->
    <script type="text/javascript" src="/js/trirand/jquery.jqmultiselect.min.js"></script>    
    <style type="text/css">    
        body, html { font-size: 80%; }
    <form id="Form1" runat="server">
    <table cellpadding="10" cellspacing="10">
            <td valign="top">

                 <asp:SqlDataSource runat="server" 
                        ConnectionString="<%$ ConnectionStrings:SQL2008_661086_trirandEntities %>"        
                        SelectCommand="SELECT DISTINCT [ShipName] FROM [Orders]">
    <br /><br /><br />
    <br /><br /><br />
        <trirand:codetabs runat="server" ID="tabs"></trirand:codetabs>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace JQSuiteASPNETExample.examples.multiselect.loaddatabase
    public partial class _default1 : System.Web.UI.Page
        protected void Page_Load(object sender, EventArgs e)

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" />