How could I enable Skin Selection option in XAF web project

Hello Manoj,

Would you please post a screenshot of the feature you saw in our examples?

It looks like you are talking about the Classic Web UI and its Choose Theme action. Refer to the corresponding section under the Concepts > UI Construction > ASP.NET Web Application Appearance  article to learn more about it.

The New Web UI, which you are likely using, provides only one theme so far, so there is no skin selector for it. On the other hand, you can enable the capability to select predefined theme font and base color, as shown in our XCRM demo.
To add and customize this feature in your project, do the following:

1. Copy and include the "C:\Users\Public\Documents\DevExpress Demos 16.2\Components\eXpressApp Framework\XCRM\CS\XCRM.Web\BaseColorSelector" folder in the YourSolutionName.Web project.
2. Copy and include the "C:\Users\Public\Documents\DevExpress Demos 16.2\Components\eXpressApp Framework\XCRM\CS\XCRM.Web\CustomDefaultVerticalTemplateContent.xx" files in the YourSolutionName.Web project and optionally customize the custom template in Visual Studio to meet your business requirements.
3. In the YourSolutionName.Web/Global.asax.cs file, add the WebApplication.Instance.Settings.DefaultVerticalTemplateContentPath = "CustomDefaultVerticalTemplateContent.ascx"; line to the Session_Start method after the WebApplication.SetInstance call.
4. In the YourSolutionName.Web/Global.asax.cs file, add the following method into the Global class:

C#
protected void Application_BeginRequest(object sender, EventArgs e) {  
    ASPxWebControl.GlobalThemeBaseColor = DevExpress.Web.Demos.Utils.CurrentBaseColor;  
    ASPxWebControl.GlobalThemeFont = DevExpress.Web.Demos.Utils.CurrentFont;  
}  

Refer to the Task-Based Help > How to: Customize an ASP.NET Template article to learn more about this customization process.

I am looking forward to hearing of your results.