Programmer - fluent nhibernate manytomany mapping

Programmer Question

Hi guys,
I am trying to map these entities
Messages table fields are Id generated Id,SentFrom int, sentTo int
where Sentfrom and sentTo are linked to the users table
I also have a linker table
MessageUser table with userId and MessageId

CREATE TABLE [dbo].[MessageUser](
[MessageId] [int] NOT NULL,
[UserId] [int] NOT NULL,

CONSTRAINT [PK_MessageUser] PRIMARY KEY CLUSTERED
(
[MessageId] ASC,
[UserId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

ALTER TABLE [dbo].[MessageUser] WITH CHECK ADD CONSTRAINT [FK_MessageUser_Messages] FOREIGN KEY([MessageId])
REFERENCES [dbo].[Messages] ([Id])
GO
ALTER TABLE [dbo].[MessageUser] CHECK CONSTRAINT [FK_MessageUser_Messages]
GO
ALTER TABLE [dbo].[MessageUser] WITH CHECK ADD CONSTRAINT [FK_MessageUser_Users] FOREIGN KEY([UserId])
REFERENCES [dbo].[Users] ([Id])
GO
ALTER TABLE [dbo].[MessageUser] CHECK CONSTRAINT [FK_MessageUser_Users]
GO

I think the db design is Ok but I can't figure out the best way to map the entities
my ultimate goal to be able to get the Messages sentTo and message sentFrom using the user and the message entities.
Any idea how to achieve that goal.

Thanks