OOP help

Could somebody please finish off this bit of code for me? I'm trying to do things properly now - ie in OOP, and I'm not quite sure how to proceed.

It's just a parallex star field with stars of 2 speeds and the background stars vary in brightness.

Many thanks, Steve

Rem

  Scrolling Starfield

End Rem

Framework BRL.Basic
Import BRL.glmax2d
Import BRL.pngloader
Strict

'----------------------------------------------------------
' global variables

Const X_RES = 800, Y_RES = 600 : Int

Global star_list:Tlist = CreateList()

'----------------------------------------------------------
' define types

Type star

  Field x : Int
  Field y : Int
  Field speed : Int

  Method init_star()

    Local loop : Int
  
    For loop = 1 To 75

      Astar:star = New star
      ListAddLast star_list, star

      Astar.speed = 1
      If loop <= 50 Astar.speed = 0
      Astar.x = Rand(10,X_RES-10) ; Astar.y = Rand(10,Y_RES-10)  

    next

  End method

  Method update_star()

    If Astar.speed = 1
      Astar.y :+ 2
    else
      Astar.y :+ 1
    endif

    If Astar.y > Y_RES Astar.y = Astar.y - Y_RES

  End method

  Method draw_star()

    SetBlend(SOLIDBLEND) ; SetColor(255,255,255)

    For Astar:star = EachIn star_list

      If Astar.speed = 1

        SetColor(255,255,255)
        Plot(Astar.x,Astar.y)

      Else

        Local star_bright = Rand(1,100)

        If star_bright < 11
          SetColor(255,255,255)
        else
          SetColor(128,128,128)
        endif

        Plot(Astar.x,Astar.y) 

      EndIf

    next

  End method

End Type

'----------------------------------------------------------

Graphics(X_RES,Y_RES,32,0)
HideMouse()

Repeat

  Cls

Until KeyHit(KEY_ESCAPE)