date_add
To add days/hours/minutes/seconds to a particular date you may use the + operator and the TimeSpan object. Examples:
${System.DateTime.Now + System.TimeSpan.FromDays(1)}
${System.DateTime.Now + System.TimeSpan.FromHours(1)}
${System.DateTime.Now + System.TimeSpan.FromMinutes(1)}
${System.DateTime.Now + System.TimeSpan.FromSeconds(1)}