var albumid = 123456789;
var photos = Api.Photo.Get(new PhotoGetParams
{
	AlbumId = PhotoAlbumType.Id(albumid),
	OwnerId = Api.UserId.Value
});
Api.Messages.Send(new MessagesSendParams
{
	Attachments = photos,
	Message = "Message",
	PeerId = Api.UserId.Value
});