Mouseover and rollovers urgent!please help

hi! i am doing a flash website, my gallery is made up of small thumbnails, now what i want to achieve is, i want to have the enlarged version of the thumbnailed showen somewhere specific on stage when a mouse is rolled over the hit area,and i want it to disapper when the mouse is moved away frm the hit area, i knw this sounds very easy, bt i tried, bt i cnt achieve what i really want
thanks in advance