Restrictions on C # generic type parameters (where T:class,new ()) __c#

is not very familiar with the generics, plus or C #, more is confused, see a

  Public List<t> convertto<t> (DataTable DataTable) where T:new ()

is at a loss.
The following is an explanation on MSDN:

constraint	Description
where t:struct	This type parameter must be a value type, except for all types of nullable types.
where T:class	This type parameter must be a reference type.
where T:new ()	This type parameter must have a public parameterless constructor. When used with other constraint parameters, the new () constraint must be last.
where T:	This type parameter must be or inherit from the specified base class.
where T:	This type parameter must either be or implement the specified interface.
where T:u	Type parameter T must be or be inherited from a type parameter.

Original text in this (English)
So much clearer now ~