If you mean 'How do I return back to the previous buffer?' then you use the GraphicsBuffer() function:
gb=GraphicsBuffer() gfxStarfield=CreateImage(32,32,10) ; loop through each frame of the graphic we just made For t = 0 To 9 ; Set the drawing buffer to the graphic frame so we can write on it SetBuffer ImageBuffer(gfxStarfield,t) ; put 50 stars in the frame at random locations For y = 1 To 50 Plot Rand(32),Rand(32) Next Next SetBuffer gb