Dropdown Alert messages should be inline

I have 3 dropdownlists, and i used javascript to validate it with alert, but i want these alert error messages to be display inline below the dropdown.
HTML is :
<table class="tabularform1"> <tr> <td class="leftLable" style="padding-bottom:5px;width: 188px;"> <asp:Label ID="lblEMpCode" runat="server">Employee Code<span style="color: #ce162e!important">*</span></asp:Label>&nbsp;</td> <td><asp:TextBox ID="txtEmpCode" runat="server" MaxLength="5" CssClass="txtfld-popup45"></asp:TextBox> <cc1:TextBoxWatermarkExtender ID="txtEmpCode_TextBoxWatermarkExtender" runat="server" TargetControlID="txtEmpCode" Watermar ...