Hi,

You need to create and register a menurendering notification

public class MemberTreeNotificationHandler : INotificationHandler<MenuRenderingNotification>
{
    /// <summary>
    /// Adds a translate action to the Dictionary menu
    /// </summary>
    /// <param name="notification">The notification details</param>
    public void Handle(MenuRenderingNotification notification)
    {
        if (notification.TreeAlias.Equals(Constants.Trees.Members))
        {
            var menuItem = new Umbraco.Cms.Core.Models.Trees.MenuItem("sendValidation", "SendValidation");
            menuItem.AdditionalData.Add("actionView", "/App_Plugins/MediaWizards/resendValidation.html");
            menuItem.Icon = "shuffle";
            notification.Menu.Items.Add(menuItem);
        }
    }
}

Then register using a composer

public class MediaWizComposer : IComposer
{
    public void Compose(IUmbracoBuilder builder)
    {
        builder.AddNotificationHandler<MenuRenderingNotification, MemberTreeNotificationHandler>();
    }
}