Write following code.
DataUsersClassesDataContext dataUsers = new DataUsersClassesDataContext(); // LINQ object
// Users is the database table inside the LINQ object, AutoID is the primary key that is used to compare the value
ThisUser user = dataUsers.Users.Single(u => u.AutoID == XXXX);
if (user != null)
{
// set properties
user.Active = active;
user.Name = "MyName";
user.Role = role;
user.ThisDateTime = DateTime.Parse(thisDateTime);
dataUsers.SubmitChanges(); // submit the changes that will update the database.
}