The following is a hello world WinForms example:

    open System
    open System.Windows.Forms

    let form = new Form()
    do form.Width  <- 400
    do form.Height <- 300
    do form.Text <- "Hello World Form"

    (* Menu bar, menus *)
    let mMain = form.Menu <- new MainMenu()
    let mFile = form.Menu.MenuItems.Add("&File")
    let miQuit  = new MenuItem("&Quit")
    let _ = mFile.MenuItems.Add(miQuit)

    (* RichTextView *)
    let textB = new RichTextBox()
    do textB.Dock <- DockStyle.Fill  
    do textB.Text <- "Hello World\n\nCongratulations!"
    do form.Controls.Add(textB)    

    (* callbacks *)
    let opExitForm sender args = form.Close ()
    do miQuit .add_Click (new EventHandler(opExitForm))

    (* run! *)  
    do Application.Run(form)

If you save the above as

    \dev\src\helloforms.fs

then assuming fsc is in your path, you can compile and run it as follows:

    cd \dev\src
    fsc \dev\src\helloforms.fs
    helloforms.exe