Making a column readonly in GridView in ASP.Net

<asp:TextBox ID="TextBox1" runat="server" BackColor="#3877C5" Font-Bold="True"
Font-Names="Calibri" Font-Size="X-Large" ForeColor="White" Width="924px"> Software MisMatch Report



<asp:SqlDataSource ID="Vendor" runat="server" ConnectionString="Data Source=10.128.32.190;Initial Catalog=SYBIDEV;Integrated Security=True"

SelectCommand="SELECT DISTINCT Vendor FROM tblFactSoftwareStg">






<asp:GridView ID="GridView1" runat="server" AllowPaging="True"
AllowSorting="True" AutoGenerateColumns="False" CellPadding="4"
DataSourceID="SI" ForeColor="#333333" GridLines="None"
AutoGenerateEditButton="True"
onselectedindexchanged="GridView1_SelectedIndexChanged" PageSize="20"
Font-Names="Calibri">
<alternatingrowstyle backcolor="White" font-bold="False" font-names="Calibri">
Font-Size="Medium" />
<columns> <asp:BoundField DataField="Vendor" HeaderText="Vendor"
SortExpression="Vendor" ReadOnly="True" />
<asp:BoundField DataField="SoftwareName" HeaderText="SoftwareName"
SortExpression="SoftwareName" />
<asp:BoundField DataField="Version" HeaderText="Version"
SortExpression="Version" />
<asp:BoundField DataField="LicenseType" HeaderText="LicenseType"
SortExpression="LicenseType" />
<asp:BoundField DataField="GenericSoftwareName"
HeaderText="GenericSoftwareName" SortExpression="GenericSoftwareName" />
<editrowstyle backcolor="#99CCFF">
<footerstyle backcolor="#507CD1" font-bold="True" forecolor="White">
<HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
<pagerstyle backcolor="#2461BF" forecolor="White" horizontalalign="Center">
<rowstyle backcolor="#EFF3FB">
<SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />
<sortedascendingcellstyle backcolor="#F5F7FB">
<sortedascendingheaderstyle backcolor="#6D95E1">
<sorteddescendingcellstyle backcolor="#E9EBEF">
<sorteddescendingheaderstyle backcolor="#4870BE">

<asp:SqlDataSource ID="SI" runat="server"
ConnectionString="Data Source=10.128.32.190;Initial Catalog=SYBIDEV;Integrated Security=True"
ProviderName="System.Data.SqlClient" SelectCommand="select distinct Vendor,SoftwareName,Version,LicenseType,GenericSoftwareName from tblFactSoftwareStg where (GenericSoftwareName='NA' or GenericSoftwareName is null or LicenseType='NA' or LicenseType is null) "



UpdateCommand="exec SCCM_Test @Vendor=@Vendor,@SoftwareName=@SoftwareName,@Version=@Version,@LicenseType=@LicenseType,@GenericSoftwareName=@GenericSoftwareName">
<updateparameters>
<asp:Parameter Name="Vendor" />
<asp:Parameter Name="SoftwareName" />
<asp:Parameter Name="Version" />
<asp:Parameter Name="LicenseType" />
<asp:Parameter Name="GenericSoftwareName" />